diff --git a/include/etl/private/chrono/day.h b/include/etl/private/chrono/day.h
index 6dfb15f6..4a3aa2d3 100644
--- a/include/etl/private/chrono/day.h
+++ b/include/etl/private/chrono/day.h
@@ -171,9 +171,9 @@ namespace etl
 
       //***********************************************************************
       /// Compare day with another.
-      /// if day < other, returns -1;
-      /// else if day > other, returns 1;
-      /// else returns 0;
+      /// if day < other, returns -1
+      /// else if day > other, returns 1
+      /// else returns 0
       //***********************************************************************
       ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const day& other) const ETL_NOEXCEPT 
@@ -336,9 +336,9 @@ namespace etl
 #if ETL_HAS_CHRONO_LITERALS_DAY
 namespace etl
 {
-  namespace literals
+  inline namespace literals
   {
-    namespace chrono_literals
+    inline namespace chrono_literals
     {
 #if ETL_USING_VERBOSE_CHRONO_LITERALS
   inline ETL_CONSTEXPR14 etl::chrono::day operator ""_day(unsigned long long d) noexcept
diff --git a/include/etl/private/chrono/duration.h b/include/etl/private/chrono/duration.h
index b16ed6ba..a1cd5b71 100644
--- a/include/etl/private/chrono/duration.h
+++ b/include/etl/private/chrono/duration.h
@@ -106,8 +106,8 @@ namespace etl
     {
     public:
 
-      typedef TRep rep;
-      typedef typename TPeriod::type period;
+      using rep    = TRep;
+      using period =  typename TPeriod::type;
 
       //***********************************************************************
       ETL_CONSTEXPR duration() ETL_NOEXCEPT
@@ -285,9 +285,9 @@ namespace etl
 
       //***********************************************************************
       /// Compare duration with another.
-      /// if duration < other, returns -1;
-      /// else if duration > other, returns 1;
-      /// else returns 0;
+      /// if duration < other, returns -1
+      /// else if duration > other, returns 1
+      /// else returns 0
       //***********************************************************************
       template <typename TRep2, typename TPeriod2>
       ETL_CONSTEXPR14 int compare(const duration<TRep2, TPeriod2>& other) const ETL_NOEXCEPT 
@@ -313,22 +313,22 @@ namespace etl
     /// Duration types
     //***********************************************************************
 #if (ETL_USING_64BIT_TYPES)
-    typedef etl::chrono::duration<int64_t, etl::nano>              nanoseconds;
-    typedef etl::chrono::duration<int64_t, etl::micro>             microseconds;
-    typedef etl::chrono::duration<int64_t, etl::milli>             milliseconds;
-    typedef etl::chrono::duration<int64_t, etl::ratio<1U> >        seconds;
+    using nanoseconds  = etl::chrono::duration<int64_t, etl::nano>;
+    using microseconds = etl::chrono::duration<int64_t, etl::micro>;
+    using milliseconds = etl::chrono::duration<int64_t, etl::milli>;
+    using seconds      = etl::chrono::duration<int64_t, etl::ratio<1U>>;
 #else
-    typedef etl::chrono::duration<int32_t, etl::nano>              nanoseconds;
-    typedef etl::chrono::duration<int32_t, etl::micro>             microseconds;
-    typedef etl::chrono::duration<int32_t, etl::milli>             milliseconds;
-    typedef etl::chrono::duration<int32_t, etl::ratio<1U> >        seconds;
+    using nanoseconds  = etl::chrono::duration<int32_t, etl::nano>;
+    using microseconds = etl::chrono::duration<int32_t, etl::micro>;
+    using milliseconds = etl::chrono::duration<int32_t, etl::milli>;
+    using seconds      = etl::chrono::duration<int32_t, etl::ratio<1U>>;
 #endif
-    typedef etl::chrono::duration<int32_t, etl::ratio<60U> >       minutes;
-    typedef etl::chrono::duration<int32_t, etl::ratio<3600U> >     hours;
-    typedef etl::chrono::duration<int32_t, etl::ratio<86400U> >    days;
-    typedef etl::chrono::duration<int32_t, etl::ratio<604800U> >   weeks;
-    typedef etl::chrono::duration<int32_t, etl::ratio<2629746U> >  months;
-    typedef etl::chrono::duration<int32_t, etl::ratio<31556952U> > years;
+    using minutes = etl::chrono::duration<int32_t, etl::ratio<60U>>;
+    using hours   = etl::chrono::duration<int32_t, etl::ratio<3600U>>;
+    using days    = etl::chrono::duration<int32_t, etl::ratio<86400U>>;
+    using weeks   = etl::chrono::duration<int32_t, etl::ratio<604800U>>;
+    using months  = etl::chrono::duration<int32_t, etl::ratio<2629746U>>;
+    using years   = etl::chrono::duration<int32_t, etl::ratio<31556952U>>;
 
     //***********************************************************************
     /// duration_cast
@@ -336,14 +336,14 @@ namespace etl
     template <typename TToDuration, typename TRep, typename TPeriod>
     ETL_CONSTEXPR14 TToDuration duration_cast(const etl::chrono::duration<TRep, TPeriod>& d) ETL_NOEXCEPT
     {
-      typedef TRep    from_rep;
-      typedef TPeriod from_period;
+      using from_rep    = TRep    ;
+      using from_period = TPeriod ;
 
-      typedef typename TToDuration::rep    to_rep;
-      typedef typename TToDuration::period to_period;
+      using to_rep    = typename TToDuration::rep;
+      using to_period = typename TToDuration::period;
 
-      typedef typename etl::ratio_divide<from_period, to_period> ratio_divide_t;
-      typedef typename etl::common_type<from_rep, to_rep, intmax_t>::type common_t;
+      using ratio_divide_t = typename etl::ratio_divide<from_period, to_period>;
+      using common_t       = typename etl::common_type<from_rep, to_rep, intmax_t>::type;
 
       common_t ct_count = static_cast<common_t>(d.count());
       common_t ct_num   = static_cast<common_t>(ratio_divide_t::type::num);
@@ -396,13 +396,13 @@ namespace etl
   /// Find the common type of two duration types.
   //***********************************************************************
   template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
-  struct common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >
+  struct common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2>>
   {
   private:
 
-    typedef typename etl::common_type<TRep1, TRep2>::type value_type;
-    typedef etl::ratio<etl::chrono::private_chrono::gcd<TPeriod1::num, TPeriod2::num>::value,
-                       etl::chrono::private_chrono::lcm<TPeriod1::den, TPeriod2::den>::value> period_type;
+    using value_type  = typename etl::common_type<TRep1, TRep2>::type ;
+    using period_type = etl::ratio<etl::chrono::private_chrono::gcd<TPeriod1::num, TPeriod2::num>::value,
+                                   etl::chrono::private_chrono::lcm<TPeriod1::den, TPeriod2::den>::value>;
 
   public:
 
@@ -416,7 +416,7 @@ namespace etl
   ETL_CONSTEXPR14 bool operator ==(const etl::chrono::duration<TRep1, TPeriod1>& lhs, 
                                    const etl::chrono::duration<TRep2, TPeriod2>& rhs) ETL_NOEXCEPT
   {
-    typedef typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type common_t;
+    using common_t = typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type;
     
     common_t l = etl::chrono::duration_cast<common_t>(lhs);
     common_t r = etl::chrono::duration_cast<common_t>(rhs);
@@ -441,7 +441,7 @@ namespace etl
   ETL_CONSTEXPR14 bool operator <(const etl::chrono::duration<TRep1, TPeriod1>& lhs, 
                                   const etl::chrono::duration<TRep2, TPeriod2>& rhs) ETL_NOEXCEPT
   {
-    typedef typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type common_t;
+    using common_t = typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type;
 
     common_t l = etl::chrono::duration_cast<common_t>(lhs);
     common_t r = etl::chrono::duration_cast<common_t>(rhs);
@@ -487,7 +487,7 @@ namespace etl
   [[nodiscard]] constexpr auto operator <=>(const etl::chrono::duration<TRep1, TPeriod1>& lhs, 
                                             const etl::chrono::duration<TRep2, TPeriod2>& rhs) ETL_NOEXCEPT
   {
-    typedef typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type common_t;
+    using common_t = typename etl::common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2> >::type;
 
     common_t l = etl::chrono::duration_cast<common_t>(lhs);
     common_t r = etl::chrono::duration_cast<common_t>(rhs);
@@ -709,9 +709,9 @@ namespace etl
 #if ETL_HAS_CHRONO_LITERALS_DURATION
 namespace etl
 {
-  namespace literals
+  inline namespace literals
   {
-    namespace chrono_literals
+    inline namespace chrono_literals
     {
       //***********************************************************************
       /// Literal for hours duration
diff --git a/include/etl/private/chrono/hh_mm_ss.h b/include/etl/private/chrono/hh_mm_ss.h
index d044c726..4c92d2ee 100644
--- a/include/etl/private/chrono/hh_mm_ss.h
+++ b/include/etl/private/chrono/hh_mm_ss.h
@@ -44,7 +44,6 @@ namespace etl
   template <typename TDuration>
   ETL_NODISCARD
   ETL_CONSTEXPR14 
-  //typename etl::enable_if<etl::chrono::is_duration<TDuration>::value, TDuration>::type
   typename etl::enable_if<etl::is_specialization<TDuration, etl::chrono::duration>::value, TDuration>::type
     absolute(TDuration dur) ETL_NOEXCEPT
   {
diff --git a/include/etl/private/chrono/month.h b/include/etl/private/chrono/month.h
index abd98de9..890893bf 100644
--- a/include/etl/private/chrono/month.h
+++ b/include/etl/private/chrono/month.h
@@ -165,9 +165,9 @@ namespace etl
 
       //***********************************************************************
       /// Compare month with another.
-      /// if month < other, returns -1;
-      /// else if month > other, returns 1;
-      /// else returns 0;
+      /// if month < other, returns -1
+      /// else if month > other, returns 1
+      /// else returns 0
       //***********************************************************************
       ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const month& other) const ETL_NOEXCEPT 
@@ -367,68 +367,6 @@ namespace etl
     static ETL_CONSTANT etl::chrono::month November{ 11 };
     static ETL_CONSTANT etl::chrono::month December{ 12 };
 #endif
-
-    //*************************************************************************
-    /// month_day_last
-    //*************************************************************************
-    class month_day_last
-    {
-    public:
-
-      //*************************************************************************
-      /// Construct from month.
-      //*************************************************************************
-      ETL_CONSTEXPR14 explicit month_day_last(const etl::chrono::month& m_) ETL_NOEXCEPT
-        : m(m_)
-      {
-      }
-
-      //*************************************************************************
-      /// Get the month.
-      //*************************************************************************
-      ETL_CONSTEXPR14 etl::chrono::month month() const ETL_NOEXCEPT
-      {
-        return m;
-      }
-
-      //*************************************************************************
-      /// Is the contained month OK?
-      //*************************************************************************
-      bool ok() const ETL_NOEXCEPT
-      {
-        return m.ok();
-      }
-
-    private:
-
-      etl::chrono::month m;
-    };
-
-    //***********************************************************************
-    /// Equality operator
-    //***********************************************************************
-    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_day_last& mdl1, const etl::chrono::month_day_last& mdl2) ETL_NOEXCEPT
-    {
-      return (static_cast<unsigned>(mdl1.month()) == static_cast<unsigned>(mdl2.month()));
-    }
-
-    //***********************************************************************
-    /// Inequality operator
-    //***********************************************************************
-    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_day_last& mdl1, const etl::chrono::month_day_last& mdl2) ETL_NOEXCEPT
-    {
-      return !(mdl1 == mdl2);
-    }
-
-    //***********************************************************************
-    /// Spaceship operator
-    //***********************************************************************
-#if ETL_USING_CPP20
-    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::month_day_last& mdl1, const etl::chrono::month_day_last& mdl2) noexcept
-    {
-      return (static_cast<unsigned>(mdl1.month()) <=> static_cast<unsigned>(mdl2.month()));
-    }
-#endif
   }
 
   //*************************************************************************
@@ -448,20 +386,5 @@ namespace etl
   };
 #endif
 
-  //*************************************************************************
-  /// Hash function for etl::chrono::month_day_last
-  //*************************************************************************
-#if ETL_USING_8BIT_TYPES
-  template <>
-  struct hash<etl::chrono::month_day_last>
-  {
-    size_t operator()(const etl::chrono::month_day_last& mdl) const
-    {
-      etl::chrono::month::rep value = static_cast<etl::chrono::month::rep>(static_cast<unsigned>(mdl.month()));
-      const uint8_t* p = reinterpret_cast<const uint8_t*>(&value);
 
-      return etl::private_hash::generic_hash<size_t>(p, p + sizeof(value));
-    }
-  };
-#endif
 }
diff --git a/include/etl/private/chrono/month_day.h b/include/etl/private/chrono/month_day.h
index fbbb4408..f012d797 100644
--- a/include/etl/private/chrono/month_day.h
+++ b/include/etl/private/chrono/month_day.h
@@ -94,102 +94,13 @@ namespace etl
                (static_cast<unsigned>(d) <= max_day);
       }
 
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_day& lhs, 
-                                              const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.d == rhs.d) && (lhs.m == rhs.m);
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_day& lhs, 
-                                              const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
-      //*************************************************************************
-      /// Less-than operator.
-      //*************************************************************************
-      ETL_NODISCARD friend ETL_CONSTEXPR14
-        bool operator <(const etl::chrono::month_day& lhs,
-                        const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        if (lhs.month() < rhs.month())
-        {
-          return true;
-        }
-        else if (lhs.month() == rhs.month())
-        {
-          return lhs.day() < rhs.day();
-        }
-        else
-        {
-          return false;
-        }
-      }
-
-      //*************************************************************************
-      /// Less-than-equal operator.
-      //*************************************************************************
-      ETL_NODISCARD friend ETL_CONSTEXPR14
-        bool operator <=(const etl::chrono::month_day& lhs,
-                         const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        return !(rhs < lhs);
-      }
-
-      //*************************************************************************
-      /// Greater-than operator.
-      //*************************************************************************
-      ETL_NODISCARD friend ETL_CONSTEXPR14
-        bool operator >(const etl::chrono::month_day& lhs,
-                         const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        return rhs < lhs;
-      }
-
-      //*************************************************************************
-      /// Greater-than-equal operator.
-      //*************************************************************************
-      ETL_NODISCARD friend ETL_CONSTEXPR14
-        bool operator >=(const etl::chrono::month_day& lhs,
-                         const etl::chrono::month_day& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs < rhs);
-      }
-
-      //***********************************************************************
-      /// Spaceship operator
-      //***********************************************************************
-#if ETL_USING_CPP20
-      [[nodiscard]] friend constexpr auto operator <=>(const etl::chrono::month_day& lhs, 
-                                                       const etl::chrono::month_day& rhs) noexcept
-      {
-        auto cmp = lhs.month() <=> rhs.month();
-
-        if (cmp != 0)
-        {
-          return cmp;
-        }
-        else
-        {
-          return lhs.day() <=> rhs.day();
-        }
-      }
-#endif
-
       //***********************************************************************
       /// Compare month_day with another.
-      /// if month < other.month, returns -1;
-      /// else if month > other.month, returns 1;
-      /// else if day < other.day, returns -1;
-      /// else if day > other.day, returns 1;
-      /// else returns 0;
+      /// if month < other.month, returns -1
+      /// else if month > other.month, returns 1
+      /// else if day < other.day, returns -1
+      /// else if day > other.day, returns 1
+      /// else returns 0
       //***********************************************************************
       ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const month_day& other) const ETL_NOEXCEPT 
@@ -206,7 +117,215 @@ namespace etl
 
       etl::chrono::month m;
       etl::chrono::day   d;
-    };  
+    };
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_day& lhs, 
+                                            const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.day() == rhs.day()) && (lhs.month() == rhs.month());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_day& lhs, 
+                                            const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
+    //*************************************************************************
+    /// Less-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <(const etl::chrono::month_day& lhs,
+                           const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      if (lhs.month() < rhs.month())
+      {
+        return true;
+      }
+      else if (lhs.month() == rhs.month())
+      {
+        return lhs.day() < rhs.day();
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    //*************************************************************************
+    /// Less-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <=(const etl::chrono::month_day& lhs,
+                            const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(rhs < lhs);
+    }
+
+    //*************************************************************************
+    /// Greater-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >(const etl::chrono::month_day& lhs,
+                           const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      return rhs < lhs;
+    }
+
+    //*************************************************************************
+    /// Greater-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >=(const etl::chrono::month_day& lhs,
+                            const etl::chrono::month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs < rhs);
+    }
+
+    //***********************************************************************
+    /// Spaceship operator
+    //***********************************************************************
+#if ETL_USING_CPP20
+    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::month_day& lhs, 
+                                                     const etl::chrono::month_day& rhs) noexcept
+    {
+      auto cmp = lhs.month() <=> rhs.month();
+
+      if (cmp != 0)
+      {
+        return cmp;
+      }
+      else
+      {
+        return lhs.day() <=> rhs.day();
+      }
+    }
+#endif
+
+    //*************************************************************************
+    /// month_day_last
+    //*************************************************************************
+    class month_day_last
+    {
+    public:
+
+      //*************************************************************************
+      /// Construct from month.
+      //*************************************************************************
+      ETL_CONSTEXPR14 explicit month_day_last(const etl::chrono::month& m_) ETL_NOEXCEPT
+        : m(m_)
+      {
+      }
+
+      //*************************************************************************
+      /// Get the month.
+      //*************************************************************************
+      ETL_CONSTEXPR14 etl::chrono::month month() const ETL_NOEXCEPT
+      {
+        return m;
+      }
+
+      //*************************************************************************
+      /// Is the contained month OK?
+      //*************************************************************************
+      bool ok() const ETL_NOEXCEPT
+      {
+        return m.ok();
+      }
+
+      //***********************************************************************
+      /// Compare month_day with another.
+      /// if month < other.month, returns -1
+      /// else if month > other.month, returns 1
+      /// else returns 0
+      //***********************************************************************
+      ETL_NODISCARD
+      ETL_CONSTEXPR14 int compare(const month_day& other) const ETL_NOEXCEPT 
+      {
+        if (m < other.month()) return -1;
+        if (m > other.month()) return 1;
+
+        return 0;
+      }
+
+    private:
+
+      etl::chrono::month m;
+    };
+
+    //***********************************************************************
+    /// Equality operator
+    //***********************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_day_last& mdl1, 
+                                            const etl::chrono::month_day_last& mdl2) ETL_NOEXCEPT
+    {
+      return (static_cast<unsigned>(mdl1.month()) == static_cast<unsigned>(mdl2.month()));
+    }
+
+    //***********************************************************************
+    /// Inequality operator
+    //***********************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_day_last& mdl1, 
+                                            const etl::chrono::month_day_last& mdl2) ETL_NOEXCEPT
+    {
+      return !(mdl1 == mdl2);
+    }
+
+    //*************************************************************************
+    /// Less-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <(const etl::chrono::month_day_last& lhs,
+                           const etl::chrono::month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.month() < rhs.month());
+    }
+
+    //*************************************************************************
+    /// Less-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <=(const etl::chrono::month_day_last& lhs,
+                            const etl::chrono::month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return !(rhs < lhs);
+    }
+
+    //*************************************************************************
+    /// Greater-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >(const etl::chrono::month_day_last& lhs,
+                           const etl::chrono::month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return rhs < lhs;
+    }
+
+    //*************************************************************************
+    /// Greater-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >=(const etl::chrono::month_day_last& lhs,
+                            const etl::chrono::month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs < rhs);
+    }
+
+    //***********************************************************************
+    /// Spaceship operator
+    //***********************************************************************
+#if ETL_USING_CPP20
+    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::month_day_last& mdl1, const etl::chrono::month_day_last& mdl2) noexcept
+    {
+      return (static_cast<unsigned>(mdl1.month()) <=> static_cast<unsigned>(mdl2.month()));
+    }
+#endif
   }
 
   //*************************************************************************
@@ -230,5 +349,22 @@ namespace etl
     }
   };
 #endif
+
+  //*************************************************************************
+  /// Hash function for etl::chrono::month_day_last
+  //*************************************************************************
+#if ETL_USING_8BIT_TYPES
+  template <>
+  struct hash<etl::chrono::month_day_last>
+  {
+    size_t operator()(const etl::chrono::month_day_last& mdl) const
+    {
+      etl::chrono::month::rep value = static_cast<etl::chrono::month::rep>(static_cast<unsigned>(mdl.month()));
+      const uint8_t* p = reinterpret_cast<const uint8_t*>(&value);
+
+      return etl::private_hash::generic_hash<size_t>(p, p + sizeof(value));
+    }
+  };
+#endif
 }
 
diff --git a/include/etl/private/chrono/month_weekday.h b/include/etl/private/chrono/month_weekday.h
index 444f91a0..9e05692d 100644
--- a/include/etl/private/chrono/month_weekday.h
+++ b/include/etl/private/chrono/month_weekday.h
@@ -77,30 +77,31 @@ namespace etl
         return m.ok() && wdi.ok();
       }
 
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_weekday& lhs, 
-                                              const etl::chrono::month_weekday& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.m == rhs.m) && (lhs.wdi == rhs.wdi);
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_weekday& lhs, 
-                                              const etl::chrono::month_weekday& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
     private:
 
       etl::chrono::month m;
       etl::chrono::weekday_indexed wdi;
     };
 
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_weekday& lhs, 
+                                            const etl::chrono::month_weekday& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.month() == rhs.month()) &&
+             (lhs.weekday_indexed() == rhs.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_weekday& lhs, 
+                                            const etl::chrono::month_weekday& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
     //*************************************************************************
     /// Construct from month and weekday_last.
     //*************************************************************************
@@ -145,29 +146,29 @@ namespace etl
         return m.ok() && wdl.ok();
       }
 
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_weekday_last& lhs, 
-                                              const etl::chrono::month_weekday_last& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.m == rhs.m) && (lhs.wdl == rhs.wdl);
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_weekday_last& lhs, 
-                                              const etl::chrono::month_weekday_last& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
     private:
 
       etl::chrono::month m;
       etl::chrono::weekday_last wdl;
     };  
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::month_weekday_last& lhs, 
+                                            const etl::chrono::month_weekday_last& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.month() == rhs.month()) && (lhs.weekday_last() == rhs.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::month_weekday_last& lhs, 
+                                            const etl::chrono::month_weekday_last& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
   }
 
   //*************************************************************************
diff --git a/include/etl/private/chrono/time_point.h b/include/etl/private/chrono/time_point.h
index 142ae385..6faad033 100644
--- a/include/etl/private/chrono/time_point.h
+++ b/include/etl/private/chrono/time_point.h
@@ -78,7 +78,7 @@ namespace etl
       /// Copy construct from another time_point with a different duration type.
       //***************************************************************************
       template <typename TDuration2>
-      explicit time_point(const time_point<clock, TDuration2>& rhs) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 explicit time_point(const time_point<clock, TDuration2>& rhs) ETL_NOEXCEPT
         : dur(rhs.time_since_epoch())
       {
       }
@@ -86,7 +86,7 @@ namespace etl
       //***************************************************************************
       /// Assignment operator.
       //***************************************************************************
-      time_point& operator =(const time_point& rhs) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 time_point& operator =(const time_point& rhs) ETL_NOEXCEPT
       {
         dur = rhs.dur;
 
@@ -105,7 +105,7 @@ namespace etl
       //***************************************************************************
       /// Adds a duration.
       //***************************************************************************
-      time_point& operator +=(const duration& rhs) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 time_point& operator +=(const duration& rhs) ETL_NOEXCEPT
       {
         dur += rhs;
 
@@ -115,7 +115,7 @@ namespace etl
       //***************************************************************************
       /// Subtracts a duration.
       //***************************************************************************
-      time_point& operator -=(const duration& rhs) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 time_point& operator -=(const duration& rhs) ETL_NOEXCEPT
       {
         dur -= rhs;
 
@@ -140,6 +140,21 @@ namespace etl
         return time_point(duration::max());
       }
 
+      //***********************************************************************
+      /// Compare day with another.
+      /// if time_point < other, returns -1
+      /// else if time_point > other, returns 1
+      /// else returns 0
+      //***********************************************************************
+      ETL_NODISCARD
+      ETL_CONSTEXPR14 int compare(const time_point& other) const ETL_NOEXCEPT 
+      {
+          if (dur < other.dur) return -1;
+          if (dur > other.dur) return 1;
+
+          return 0;
+      }
+
     private:
 
       duration dur;
diff --git a/include/etl/private/chrono/year.h b/include/etl/private/chrono/year.h
index 7785b206..afef9cce 100644
--- a/include/etl/private/chrono/year.h
+++ b/include/etl/private/chrono/year.h
@@ -187,6 +187,21 @@ namespace etl
         return static_cast<int>(value);
       }
 
+      //***********************************************************************
+      /// Compare year with another.
+      /// if year < other, returns -1
+      /// else if year > other, returns 1
+      /// else returns 0
+      //***********************************************************************
+      ETL_NODISCARD
+      ETL_CONSTEXPR14 int compare(const year& other) const ETL_NOEXCEPT 
+      {
+        if (value < other.value) return -1;
+        if (value > other.value) return 1;
+
+        return 0;
+      }
+
     private:
 
       rep value;
@@ -334,9 +349,9 @@ namespace etl
 #if ETL_HAS_CHRONO_LITERALS_YEAR
 namespace etl
 {
-  namespace literals
+  inline namespace literals
   {
-    namespace chrono_literals
+    inline namespace chrono_literals
     {
       //***********************************************************************
       /// Literal for years
diff --git a/include/etl/private/chrono/year_month.h b/include/etl/private/chrono/year_month.h
index 90386396..672aadd6 100644
--- a/include/etl/private/chrono/year_month.h
+++ b/include/etl/private/chrono/year_month.h
@@ -86,115 +86,15 @@ namespace etl
         return y.ok() && m.ok();
       }
 
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::year_month& ym,
-                                                                const etl::chrono::years&      dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year() + dy, ym.month());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::years&      dy,
-                                                                const etl::chrono::year_month& ym) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year() + dy, ym.month());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::year_month& ym,
-                                                                const etl::chrono::months&     dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year(), ym.month() + dm);
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::months& dm,
-                                                                const etl::chrono::year_month& ym) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year(), ym.month() + dm);
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator -(const etl::chrono::year_month& ym,
-                                                                const etl::chrono::years&      dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year() - dy, ym.month());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month operator -(const etl::chrono::year_month& ym,
-                                                                const etl::chrono::months&     dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month(ym.year(), ym.month() - dm);
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::year_month
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::months operator -(const etl::chrono::year_month& ym1,
-                                                            const etl::chrono::year_month& ym2) ETL_NOEXCEPT
-      {
-        return etl::chrono::months(static_cast<int>(((int(ym1.year()) - int(ym2.year())) * 12) + (unsigned(ym1.month()) - unsigned(ym2.month()))));
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month& lhs, 
-                                              const etl::chrono::year_month& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.y == rhs.y) && (lhs.m == rhs.m);
-      }
-
-      //*************************************************************************
-      /// Inequality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month& lhs, 
-                                              const etl::chrono::year_month& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
-      //***********************************************************************
-      /// Spaceship operator
-      //***********************************************************************
-#if ETL_USING_CPP20
-      [[nodiscard]] friend constexpr auto operator <=>(const etl::chrono::year_month& lhs, 
-                                                       const etl::chrono::year_month& rhs) ETL_NOEXCEPT
-      {
-        auto cmp = lhs.year()<=> rhs.year();
-
-        if (cmp != 0)
-        {
-          return cmp;
-        }
-        else
-        {
-          return lhs.month() <=> rhs.month();
-        }
-      }
-#endif
-
       //***********************************************************************
       /// Compare year_month with another.
-      /// if month < other.month, returns -1;
-      /// else if month > other.month, returns 1;
-      /// else if day < other.day, returns -1;
-      /// else if day > other.day, returns 1;
-      /// else returns 0;
+      /// if month < other.month, returns -1
+      /// else if month > other.month, returns 1
+      /// else if day < other.day, returns -1
+      /// else if day > other.day, returns 1
+      /// else returns 0
       //***********************************************************************
+      ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const year_month& other) const ETL_NOEXCEPT 
       {
         if (y < other.y) return -1;
@@ -209,7 +109,159 @@ namespace etl
 
       etl::chrono::year  y;
       etl::chrono::month m;
-    };  
+    };
+
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::year_month& ym,
+                                                              const etl::chrono::years&      dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year() + dy, ym.month());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::years&      dy,
+                                                              const etl::chrono::year_month& ym) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year() + dy, ym.month());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::year_month& ym,
+                                                              const etl::chrono::months&     dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year(), ym.month() + dm);
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator +(const etl::chrono::months& dm,
+                                                              const etl::chrono::year_month& ym) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year(), ym.month() + dm);
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator -(const etl::chrono::year_month& ym,
+                                                              const etl::chrono::years&      dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year() - dy, ym.month());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month operator -(const etl::chrono::year_month& ym,
+                                                              const etl::chrono::months&     dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month(ym.year(), ym.month() - dm);
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::year_month
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::months operator -(const etl::chrono::year_month& ym1,
+                                                          const etl::chrono::year_month& ym2) ETL_NOEXCEPT
+    {
+      return etl::chrono::months(static_cast<int>(((int(ym1.year()) - int(ym2.year())) * 12) + (unsigned(ym1.month()) - unsigned(ym2.month()))));
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month& lhs, 
+                                            const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.year() == rhs.year()) && (lhs.month() == rhs.month());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month& lhs, 
+                                            const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
+    //*************************************************************************
+    /// Less-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <(const etl::chrono::year_month& lhs,
+                           const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      if (lhs.year() < rhs.year())
+      {
+        return true;
+      }
+      else if (lhs.year() == rhs.year())
+      {
+        return lhs.month() < rhs.month();
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    //*************************************************************************
+    /// Less-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <=(const etl::chrono::year_month& lhs,
+                            const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      return !(rhs < lhs);
+    }
+
+    //*************************************************************************
+    /// Greater-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >(const etl::chrono::year_month& lhs,
+                           const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      return rhs < lhs;
+    }
+
+    //*************************************************************************
+    /// Greater-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >=(const etl::chrono::year_month& lhs,
+                            const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs < rhs);
+    }
+
+    //***********************************************************************
+    /// Spaceship operator
+    //***********************************************************************
+#if ETL_USING_CPP20
+    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::year_month& lhs, 
+                                                     const etl::chrono::year_month& rhs) ETL_NOEXCEPT
+    {
+      auto cmp = lhs.year()<=> rhs.year();
+
+      if (cmp != 0)
+      {
+        return cmp;
+      }
+      else
+      {
+        return lhs.month() <=> rhs.month();
+      }
+    }
+#endif
   }
 
   //*************************************************************************
diff --git a/include/etl/private/chrono/year_month_day.h b/include/etl/private/chrono/year_month_day.h
index ba9993e6..bff1ef5d 100644
--- a/include/etl/private/chrono/year_month_day.h
+++ b/include/etl/private/chrono/year_month_day.h
@@ -123,7 +123,7 @@ namespace etl
       }
 
       //*************************************************************************
-      /// Construct from sys_days.
+      /// Construct from local_days.
       //*************************************************************************
       ETL_CONSTEXPR14 year_month_day(const etl::chrono::local_days& ld) ETL_NOEXCEPT
       {
@@ -175,111 +175,54 @@ namespace etl
       }
 
       //*************************************************************************
-      /// Adds etl::chrono::years
+      /// 
       //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::year_month_day& ymd,
-                                                                    const etl::chrono::years&          dy) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 etl::chrono::year_month_day& operator +=(const etl::chrono::years& dy) ETL_NOEXCEPT
       {
-        return etl::chrono::year_month_day(ymd.year() + dy, ymd.month(), ymd.day());
+        y += dy;
+
+        return *this;
       }
 
       //*************************************************************************
-      /// Adds etl::chrono::years
+      /// 
       //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::years&          dy,
-                                                                    const etl::chrono::year_month_day& ymd) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 etl::chrono::year_month_day& operator +=(const etl::chrono::months& dm) ETL_NOEXCEPT
       {
-        return etl::chrono::year_month_day(ymd.year() + dy, ymd.month(), ymd.day());
+        m += dm;
+
+        return *this;
       }
 
       //*************************************************************************
-      /// Adds etl::chrono::months
+      /// 
       //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::year_month_day& ymd,
-                                                                    const etl::chrono::months&         dm) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 etl::chrono::year_month_day& operator -=(const etl::chrono::years& dy) ETL_NOEXCEPT
       {
-        return etl::chrono::year_month_day(ymd.year(), ymd.month() + dm, ymd.day());
+        y -= dy;
+
+        return *this;
       }
 
       //*************************************************************************
-      /// Adds etl::chrono::months
+      /// 
       //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::months&         dm,
-                                                                    const etl::chrono::year_month_day& ymd) ETL_NOEXCEPT
+      ETL_CONSTEXPR14 etl::chrono::year_month_day& operator -=(const etl::chrono::months& dm) ETL_NOEXCEPT
       {
-        return etl::chrono::year_month_day(ymd.year(), ymd.month() + dm, ymd.day());
+        m -= dm;
+
+        return *this;
       }
 
-      //*************************************************************************
-      /// Subtracts etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator -(const etl::chrono::year_month_day& ymd,
-                                                                    const etl::chrono::years&      dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day(ymd.year() - dy, ymd.month(), ymd.day());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day operator -(const etl::chrono::year_month_day& ymd,
-                                                                    const etl::chrono::months&     dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day(ymd.year(), ymd.month() - dm, ymd.day());
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_day& lhs, 
-                                              const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.y == rhs.y) && (lhs.m == rhs.m) && (lhs.d == rhs.d);
-      }
-
-      //*************************************************************************
-      /// Inequality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_day& lhs, 
-                                              const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
-      //***********************************************************************
-      /// Spaceship operator
-      //***********************************************************************
-#if ETL_USING_CPP20
-      [[nodiscard]] friend constexpr auto operator <=>(const etl::chrono::year_month_day& lhs, 
-                                                       const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
-      {
-        auto cmp = lhs.year() <=> rhs.year();
-
-        if (cmp != 0)
-        {
-          return cmp;
-        }
-
-        cmp = lhs.month() <=> rhs.month();
-
-        if (cmp != 0)
-        {
-          return cmp;
-        }
-
-        return lhs.day() <=> rhs.day();
-      }
-#endif
-
       //***********************************************************************
       /// Compare year_month_day with another.
-      /// if year < other.year, returns -1;
-      /// else if year > other.year, returns 1;
-      /// if month < other.month, returns -1;
-      /// else if month > other.month, returns 1;
-      /// else if day < other.day, returns -1;
-      /// else if day > other.day, returns 1;
-      /// else returns 0;
+      /// if year < other.year, returns -1
+      /// else if year > other.year, returns 1
+      /// if month < other.month, returns -1
+      /// else if month > other.month, returns 1
+      /// else if day < other.day, returns -1
+      /// else if day > other.day, returns 1
+      /// else returns 0
       //***********************************************************************
       ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const year_month_day& other) const ETL_NOEXCEPT 
@@ -362,6 +305,163 @@ namespace etl
       etl::chrono::day   d;
     };
 
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::year_month_day& ymd,
+                                                                  const etl::chrono::years&          dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year() + dy, ymd.month(), ymd.day());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::years&          dy,
+                                                                  const etl::chrono::year_month_day& ymd) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year() + dy, ymd.month(), ymd.day());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::year_month_day& ymd,
+                                                                  const etl::chrono::months&         dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year(), ymd.month() + dm, ymd.day());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator +(const etl::chrono::months&         dm,
+                                                                  const etl::chrono::year_month_day& ymd) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year(), ymd.month() + dm, ymd.day());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator -(const etl::chrono::year_month_day& ymd,
+                                                                  const etl::chrono::years&      dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year() - dy, ymd.month(), ymd.day());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day operator -(const etl::chrono::year_month_day& ymd,
+                                                                  const etl::chrono::months&     dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day(ymd.year(), ymd.month() - dm, ymd.day());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_day& lhs, 
+                                            const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.year()  == rhs.year())  &&
+             (lhs.month() == rhs.month()) &&
+             (lhs.day()   == rhs.day());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_day& lhs, 
+                                            const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
+    //*************************************************************************
+    /// Less-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <(const etl::chrono::year_month_day& lhs,
+                           const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      if (lhs.year() < rhs.year())
+      {
+        return true;
+      }
+      else if (lhs.year() == rhs.year())
+      {
+        if (lhs.month() < rhs.month())
+        {
+          return true;
+        }
+        else if (lhs.month() == rhs.month())
+        {
+          return (lhs.day() < rhs.day());
+        }
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    //*************************************************************************
+    /// Less-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <=(const etl::chrono::year_month_day& lhs,
+                            const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(rhs < lhs);
+    }
+
+    //*************************************************************************
+    /// Greater-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >(const etl::chrono::year_month_day& lhs,
+                           const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      return rhs < lhs;
+    }
+
+    //*************************************************************************
+    /// Greater-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >=(const etl::chrono::year_month_day& lhs,
+                            const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs < rhs);
+    }
+
+    //***********************************************************************
+    /// Spaceship operator
+    //***********************************************************************
+#if ETL_USING_CPP20
+    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::year_month_day& lhs, 
+                                                     const etl::chrono::year_month_day& rhs) ETL_NOEXCEPT
+    {
+      auto cmp = lhs.year() <=> rhs.year();
+
+      if (cmp != 0)
+      {
+        return cmp;
+      }
+
+      cmp = lhs.month() <=> rhs.month();
+
+      if (cmp != 0)
+      {
+        return cmp;
+      }
+
+      return lhs.day() <=> rhs.day();
+    }
+#endif
+
     //*************************************************************************
     /// year_month_day_last
     //*************************************************************************
@@ -466,114 +566,13 @@ namespace etl
         return *this;
       }
 
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::year_month_day_last& ymdl,
-                                                                         const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year() + dy, ymdl.month_day_last());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::years& dy,
-                                                                         const etl::chrono::year_month_day_last& ymdl) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year() + dy, ymdl.month_day_last());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::year_month_day_last& ymdl,
-                                                                         const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() + dm));
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::months& dm,
-                                                                         const etl::chrono::year_month_day_last& ymdl) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() + dm));
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator -(const etl::chrono::year_month_day_last& ymdl,
-                                                                         const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year() - dy, ymdl.month_day_last());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator -(const etl::chrono::year_month_day_last& ymdl,
-                                                                         const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() - dm));
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_day_last& lhs, 
-                                              const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.y == rhs.y) && (lhs.m == rhs.m);
-      }
-
-      //*************************************************************************
-      /// Inequality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_day_last& lhs, 
-                                              const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
-      //***********************************************************************
-      /// Spaceship operator
-      //***********************************************************************
-#if ETL_USING_CPP20
-      [[nodiscard]] friend constexpr auto operator <=>(const etl::chrono::year_month_day_last& lhs, 
-                                                       const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
-      {
-        auto cmp1 = lhs.year() <=> rhs.year();
-
-        if (cmp1 != 0)
-        {
-          return cmp1;
-        }
-        else
-        {
-          auto cmp2 = lhs.month() <=> rhs.month();
-
-          if (cmp2 != 0)
-          {
-            return cmp2;
-          }
-          else
-          {
-            return lhs.month() <=> rhs.month();
-          }
-        }
-      }
-#endif
-
       //***********************************************************************
       /// Compare year_month_day with another.
-      /// if year < other.year, returns -1;
-      /// else if year > other.year, returns 1;
-      /// if month < other.month, returns -1;
-      /// else if month > other.month, returns 1;
-      /// else returns 0;
+      /// if year < other.year, returns -1
+      /// else if year > other.year, returns 1
+      /// if month < other.month, returns -1
+      /// else if month > other.month, returns 1
+      /// else returns 0
       //***********************************************************************
       ETL_NODISCARD
       ETL_CONSTEXPR14 int compare(const year_month_day_last& other) const ETL_NOEXCEPT 
@@ -612,6 +611,60 @@ namespace etl
       etl::chrono::month m;
     };
 
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::year_month_day_last& ymdl,
+                                                                       const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year() + dy, ymdl.month_day_last());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::years& dy,
+                                                                       const etl::chrono::year_month_day_last& ymdl) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year() + dy, ymdl.month_day_last());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::year_month_day_last& ymdl,
+                                                                       const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() + dm));
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator +(const etl::chrono::months& dm,
+                                                                       const etl::chrono::year_month_day_last& ymdl) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() + dm));
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator -(const etl::chrono::year_month_day_last& ymdl,
+                                                                       const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year() - dy, ymdl.month_day_last());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_day_last operator -(const etl::chrono::year_month_day_last& ymdl,
+                                                                       const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_day_last(ymdl.year(), etl::chrono::month_day_last(ymdl.month() - dm));
+    }
+
     //*************************************************************************
     /// Construct from year_month_day_last.
     //*************************************************************************
@@ -621,6 +674,105 @@ namespace etl
       , d(ymdl.day())
     {
     }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_day_last& lhs, 
+                                            const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.year() == rhs.year()) &&
+        (lhs.month() == rhs.month());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_day_last& lhs, 
+                                            const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
+    //*************************************************************************
+    /// Less-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <(const etl::chrono::year_month_day_last& lhs,
+                           const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      if (lhs.year() < rhs.year())
+      {
+        return true;
+      }
+      else if (lhs.year() == rhs.year())
+      {
+        return (lhs.month() < rhs.month());
+      }
+      else
+      {
+        return false;
+      }
+    }
+
+    //*************************************************************************
+    /// Less-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator <=(const etl::chrono::year_month_day_last& lhs,
+                            const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return !(rhs < lhs);
+    }
+
+    //*************************************************************************
+    /// Greater-than operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >(const etl::chrono::year_month_day_last& lhs,
+                           const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return rhs < lhs;
+    }
+
+    //*************************************************************************
+    /// Greater-than-equal operator.
+    //*************************************************************************
+    ETL_NODISCARD ETL_CONSTEXPR14
+    inline bool operator >=(const etl::chrono::year_month_day_last& lhs,
+                            const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs < rhs);
+    }
+
+    //***********************************************************************
+    /// Spaceship operator
+    //***********************************************************************
+#if ETL_USING_CPP20
+    [[nodiscard]] inline constexpr auto operator <=>(const etl::chrono::year_month_day_last& lhs, 
+                                                     const etl::chrono::year_month_day_last& rhs) ETL_NOEXCEPT
+    {
+      auto cmp1 = lhs.year() <=> rhs.year();
+
+      if (cmp1 != 0)
+      {
+        return cmp1;
+      }
+      else
+      {
+        auto cmp2 = lhs.month() <=> rhs.month();
+
+        if (cmp2 != 0)
+        {
+          return cmp2;
+        }
+        else
+        {
+          return lhs.month() <=> rhs.month();
+        }
+      }
+    }
+#endif
   }
 
   //*************************************************************************
diff --git a/include/etl/private/chrono/year_month_weekday.h b/include/etl/private/chrono/year_month_weekday.h
index 58d21fa2..ef8d9b31 100644
--- a/include/etl/private/chrono/year_month_weekday.h
+++ b/include/etl/private/chrono/year_month_weekday.h
@@ -160,78 +160,6 @@ namespace etl
         return y.ok() && m.ok() && wdi.ok();
       }
 
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::year_month_weekday& ymwd,
-                                                                        const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year() + dy, ymwd.month(), ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::years& dy,
-                                                                        const etl::chrono::year_month_weekday& ymwd) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year() + dy, ymwd.month(), ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::year_month_weekday& ymwd,
-                                                                        const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() + dm, ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::months& dm,
-                                                                        const etl::chrono::year_month_weekday& ymwd) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() + dm, ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::years
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator -(const etl::chrono::year_month_weekday& ymwd,
-                                                                        const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year() - dy, ymwd.month(), ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::months
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator -(const etl::chrono::year_month_weekday& ymwd,
-                                                                        const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() - dm, ymwd.weekday_indexed());
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_weekday& lhs, 
-                                              const etl::chrono::year_month_weekday& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.y == rhs.y) && (lhs.m == rhs.m) && (lhs.wdi == rhs.wdi);
-      }
-
-      //*************************************************************************
-      /// Inequality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_weekday& lhs, 
-                                              const etl::chrono::year_month_weekday& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
       //***********************************************************************
       /// Converts to etl::chrono::sys_days
       //***********************************************************************
@@ -280,6 +208,80 @@ namespace etl
       etl::chrono::weekday_indexed wdi;
     };
 
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::year_month_weekday& ymwd,
+                                                                      const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year() + dy, ymwd.month(), ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::years& dy,
+                                                                      const etl::chrono::year_month_weekday& ymwd) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year() + dy, ymwd.month(), ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::year_month_weekday& ymwd,
+                                                                      const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() + dm, ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator +(const etl::chrono::months& dm,
+                                                                      const etl::chrono::year_month_weekday& ymwd) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() + dm, ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::years
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator -(const etl::chrono::year_month_weekday& ymwd,
+                                                                      const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year() - dy, ymwd.month(), ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::months
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday operator -(const etl::chrono::year_month_weekday& ymwd,
+                                                                      const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday(ymwd.year(), ymwd.month() - dm, ymwd.weekday_indexed());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_weekday& lhs, 
+                                            const etl::chrono::year_month_weekday& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.year() == rhs.year())   && 
+             (lhs.month() == rhs.month()) && 
+             (lhs.weekday() == rhs.weekday());
+    }
+
+    //*************************************************************************
+    /// Inequality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_weekday& lhs, 
+                                            const etl::chrono::year_month_weekday& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
+
     //*************************************************************************
     /// year_month_weekday_last
     //*************************************************************************
@@ -375,126 +377,6 @@ namespace etl
         return *this;
       }
 
-      //*************************************************************************
-      /// Adds etl::chrono::years and const etl::chrono::year_month_weekday_last.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::year_month_weekday_last& ymwdl,
-                                                                             const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year() + dy, ymwdl.month(), ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::years and const etl::chrono::year_month_weekday_last.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::years& dy,
-                                                                             const etl::chrono::year_month_weekday_last& ymwdl) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year() + dy, ymwdl.month(), ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Adds const etl::chrono::year_month_weekday_last and etl::chrono::months.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::year_month_weekday_last& ymwdl,
-                                                                             const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() + dm, ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Adds etl::chrono::months and const etl::chrono::year_month_weekday_last.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::months& dm,
-                                                                             const etl::chrono::year_month_weekday_last& ymwdl) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() + dm, ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::years from const etl::chrono::year_month_weekday_last.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator -(const etl::chrono::year_month_weekday_last& ymwdl,
-                                                                             const etl::chrono::years& dy) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year() - dy, ymwdl.month(), ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Subtracts etl::chrono::months from const etl::chrono::year_month_weekday_last
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator -(const etl::chrono::year_month_weekday_last& ymwdl,
-                                                                             const etl::chrono::months& dm) ETL_NOEXCEPT
-      {
-        return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() - dm, ymwdl.weekday_last());
-      }
-
-      //*************************************************************************
-      /// Equality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_weekday_last& lhs, 
-                                              const etl::chrono::year_month_weekday_last& rhs) ETL_NOEXCEPT
-      {
-        return (lhs.y == rhs.y) && (lhs.m == rhs.m) && (lhs.weekday() == rhs.weekday());
-      }
-
-      //*************************************************************************
-      /// Inequality operator.
-      //*************************************************************************
-      friend ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_weekday_last& lhs, 
-                                              const etl::chrono::year_month_weekday_last& rhs) ETL_NOEXCEPT
-      {
-        return !(lhs == rhs);
-      }
-
-      //***********************************************************************
-      /// Spaceship operator
-      //***********************************************************************
-#if ETL_USING_CPP20
-      [[nodiscard]] friend constexpr auto operator <=>(const etl::chrono::year_month_weekday_last& lhs, 
-                                                       const etl::chrono::year_month_weekday_last& rhs) ETL_NOEXCEPT
-      {
-        auto cmp1 = lhs.year() <=> rhs.year();
-
-        if (cmp1 != 0)
-        {
-          return cmp1;
-        }
-        else
-        {
-          auto cmp2 = lhs.month() <=> rhs.month();
-
-          if (cmp2 != 0)
-          {
-            return cmp2;
-          }
-          else
-          {
-            return lhs.weekday().c_encoding() <=> rhs.weekday().c_encoding();
-          }
-        }
-      }
-#endif
-
-      //***********************************************************************
-      /// Compare year_month_weekday with another.
-      /// if year < other.year, returns -1;
-      /// else if year > other.year, returns 1;
-      /// if month < other.month, returns -1;
-      /// else if month > other.month, returns 1;
-      /// else returns 0;
-      //***********************************************************************
-      ETL_NODISCARD
-      ETL_CONSTEXPR14 int compare(const etl::chrono::year_month_weekday_last& other) const ETL_NOEXCEPT 
-      {
-        if (y < other.y) return -1;
-        if (y > other.y) return 1;
-        if (m < other.m) return -1;
-        if (m > other.m) return 1;
-
-        return 0;
-      }
-
       //*************************************************************************
       /// Converts to etl::chrono::sys_days
       //*************************************************************************
@@ -539,6 +421,80 @@ namespace etl
       etl::chrono::month m;
       etl::chrono::weekday_last wdl;
     };
+
+    //*************************************************************************
+    /// Adds etl::chrono::years and const etl::chrono::year_month_weekday_last.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::year_month_weekday_last& ymwdl,
+                                                                           const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year() + dy, ymwdl.month(), ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::years and const etl::chrono::year_month_weekday_last.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::years& dy,
+                                                                           const etl::chrono::year_month_weekday_last& ymwdl) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year() + dy, ymwdl.month(), ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Adds const etl::chrono::year_month_weekday_last and etl::chrono::months.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::year_month_weekday_last& ymwdl,
+                                                                           const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() + dm, ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Adds etl::chrono::months and const etl::chrono::year_month_weekday_last.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator +(const etl::chrono::months& dm,
+                                                                           const etl::chrono::year_month_weekday_last& ymwdl) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() + dm, ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::years from const etl::chrono::year_month_weekday_last.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator -(const etl::chrono::year_month_weekday_last& ymwdl,
+                                                                           const etl::chrono::years& dy) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year() - dy, ymwdl.month(), ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Subtracts etl::chrono::months from const etl::chrono::year_month_weekday_last
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 etl::chrono::year_month_weekday_last operator -(const etl::chrono::year_month_weekday_last& ymwdl,
+                                                                           const etl::chrono::months& dm) ETL_NOEXCEPT
+    {
+      return etl::chrono::year_month_weekday_last(ymwdl.year(), ymwdl.month() - dm, ymwdl.weekday_last());
+    }
+
+    //*************************************************************************
+    /// Equality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator ==(const etl::chrono::year_month_weekday_last& lhs, 
+                                            const etl::chrono::year_month_weekday_last& rhs) ETL_NOEXCEPT
+    {
+      return (lhs.year() == rhs.year())   &&
+             (lhs.month() == rhs.month()) &&
+             (lhs.weekday() == rhs.weekday());
+    }
+
+    //*************************************************************************
+    /// Inequality operator.
+    //*************************************************************************
+    inline ETL_CONSTEXPR14 bool operator !=(const etl::chrono::year_month_weekday_last& lhs, 
+                                            const etl::chrono::year_month_weekday_last& rhs) ETL_NOEXCEPT
+    {
+      return !(lhs == rhs);
+    }
   }
 
   //*************************************************************************