diff --git a/include/etl/atomic/atomic_std.h b/include/etl/atomic/atomic_std.h
index 06fcef6c..76a22c93 100644
--- a/include/etl/atomic/atomic_std.h
+++ b/include/etl/atomic/atomic_std.h
@@ -135,12 +135,12 @@ namespace etl
 
   using memory_order = std::memory_order;
 
-  static ETL_CONSTANT etl::memory_order memory_order_relaxed = std::memory_order_relaxed;
-  static ETL_CONSTANT etl::memory_order memory_order_consume = std::memory_order_consume;
-  static ETL_CONSTANT etl::memory_order memory_order_acquire = std::memory_order_acquire;
-  static ETL_CONSTANT etl::memory_order memory_order_release = std::memory_order_release;
-  static ETL_CONSTANT etl::memory_order memory_order_acq_rel = std::memory_order_acq_rel;
-  static ETL_CONSTANT etl::memory_order memory_order_seq_cst = std::memory_order_seq_cst;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_relaxed = std::memory_order_relaxed;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_consume = std::memory_order_consume;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_acquire = std::memory_order_acquire;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_release = std::memory_order_release;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_acq_rel = std::memory_order_acq_rel;
+  ETL_INLINE_VAR ETL_CONSTANT etl::memory_order memory_order_seq_cst = std::memory_order_seq_cst;
 
   using atomic_bool    = etl::atomic<bool>;
   using atomic_char    = etl::atomic<char>;
diff --git a/include/etl/basic_format_spec.h b/include/etl/basic_format_spec.h
index dc198f54..cd8b3e33 100644
--- a/include/etl/basic_format_spec.h
+++ b/include/etl/basic_format_spec.h
@@ -135,65 +135,65 @@ namespace etl
   //***************************************************************************
   // Stream formatting manipulators.
   //***************************************************************************
-  static ETL_CONSTEXPR private_basic_format_spec::base_spec setbase(uint32_t base)
+  inline ETL_CONSTEXPR private_basic_format_spec::base_spec setbase(uint32_t base)
   {
     return private_basic_format_spec::base_spec(base);
   }
 
   //*********************************
-  static ETL_CONSTEXPR private_basic_format_spec::width_spec setw(uint32_t width)
+  inline ETL_CONSTEXPR private_basic_format_spec::width_spec setw(uint32_t width)
   {
     return private_basic_format_spec::width_spec(width);
   }
 
   //*********************************
   template <typename TChar>
-  static ETL_CONSTEXPR private_basic_format_spec::fill_spec<TChar> setfill(TChar fill)
+  ETL_CONSTEXPR private_basic_format_spec::fill_spec<TChar> setfill(TChar fill)
   {
     return private_basic_format_spec::fill_spec<TChar>(fill);
   }
 
   //*********************************
-  static ETL_CONSTEXPR private_basic_format_spec::precision_spec setprecision(uint32_t precision)
+  inline ETL_CONSTEXPR private_basic_format_spec::precision_spec setprecision(uint32_t precision)
   {
     return private_basic_format_spec::precision_spec(precision);
   }
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::base_spec bin(2U);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::base_spec bin(2U);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::base_spec oct(8U);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::base_spec oct(8U);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::base_spec dec(10U);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::base_spec dec(10U);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::base_spec hex(16U);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::base_spec hex(16U);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::left_spec left = private_basic_format_spec::left_spec();
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::left_spec left = private_basic_format_spec::left_spec();
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::right_spec right = private_basic_format_spec::right_spec();
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::right_spec right = private_basic_format_spec::right_spec();
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::boolalpha_spec boolalpha(true);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::boolalpha_spec boolalpha(true);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::boolalpha_spec noboolalpha(false);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::boolalpha_spec noboolalpha(false);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::uppercase_spec uppercase(true);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::uppercase_spec uppercase(true);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::uppercase_spec nouppercase(false);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::uppercase_spec nouppercase(false);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::showbase_spec showbase(true);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::showbase_spec showbase(true);
 
   //*********************************
-  static ETL_CONSTANT private_basic_format_spec::showbase_spec noshowbase(false);
+  ETL_INLINE_VAR ETL_CONSTANT private_basic_format_spec::showbase_spec noshowbase(false);
 
   //***************************************************************************
   /// basic_format_spec
diff --git a/include/etl/index_of_type.h b/include/etl/index_of_type.h
index 2d799832..7471ef22 100644
--- a/include/etl/index_of_type.h
+++ b/include/etl/index_of_type.h
@@ -41,7 +41,7 @@ namespace etl
   //***************************************************************************
   /// Defines a no-position constant.
   //***************************************************************************
-  static ETL_CONSTANT size_t index_of_type_npos = etl::integral_limits<size_t>::max;
+  ETL_INLINE_VAR ETL_CONSTANT size_t index_of_type_npos = etl::integral_limits<size_t>::max;
 
   //***************************************************************************
   /// Finds the index of a type in a variadic type parameter.
diff --git a/include/etl/private/dynamic_extent.h b/include/etl/private/dynamic_extent.h
index afcc9687..cd34d3c1 100644
--- a/include/etl/private/dynamic_extent.h
+++ b/include/etl/private/dynamic_extent.h
@@ -36,7 +36,10 @@ SOFTWARE.
 
 namespace etl
 {
-  static ETL_CONSTANT size_t dynamic_extent = etl::integral_limits<size_t>::max;
+  // ETL_INLINE_VAR gives external linkage in C++17 and later, so that etl::span,
+  // which references dynamic_extent in its public interface, can be exported from
+  // a C++20 named module without exposing a TU-local entity. See issue #1543.
+  ETL_INLINE_VAR ETL_CONSTANT size_t dynamic_extent = etl::integral_limits<size_t>::max;
 }
 
 #endif
diff --git a/include/etl/private/variant_variadic.h b/include/etl/private/variant_variadic.h
index aaedb064..924d73a3 100644
--- a/include/etl/private/variant_variadic.h
+++ b/include/etl/private/variant_variadic.h
@@ -314,7 +314,7 @@ namespace etl
   } // namespace private_variant
 
   /// Definition of variant_npos.
-  constexpr size_t variant_npos = etl::integral_limits<size_t>::max;
+  ETL_INLINE_VAR constexpr size_t variant_npos = etl::integral_limits<size_t>::max;
 
   //***********************************
   // variant. Forward declaration
diff --git a/include/etl/type_list.h b/include/etl/type_list.h
index 7cfdfaa0..0a79c964 100644
--- a/include/etl/type_list.h
+++ b/include/etl/type_list.h
@@ -44,7 +44,7 @@ namespace etl
   //***************************************************************************
   /// Defines a no-position constant.
   //***************************************************************************
-  static ETL_CONSTANT size_t type_list_npos = etl::integral_limits<size_t>::max;
+  ETL_INLINE_VAR ETL_CONSTANT size_t type_list_npos = etl::integral_limits<size_t>::max;
 
   //***************************************************************************
   // Type list forward declaration.