diff --git a/include/etl/limits.h b/include/etl/limits.h
index c032af86..996e69f5 100644
--- a/include/etl/limits.h
+++ b/include/etl/limits.h
@@ -36,7 +36,7 @@ SOFTWARE.
 #include "char_traits.h"
 #include "integral_limits.h"
 
-#if ETL_NOT_USING_STL && defined(ETL_COMPILER_ARM5)
+#if ETL_NOT_USING_STL && defined(ETL_COMPILER_ARM5) && !defined(__USE_C99_MATH)
   // Required for nan, nanf, nanl
   #define __USE_C99_MATH
 #endif
diff --git a/include/etl/type_traits.h b/include/etl/type_traits.h
index 3757f6b7..e2e5023b 100644
--- a/include/etl/type_traits.h
+++ b/include/etl/type_traits.h
@@ -736,12 +736,16 @@ namespace etl
     template <typename, typename>
     auto nonvoid_convertible(...)->etl::false_type;
   }
-
+#if defined(ETL_COMPILER_ARM5)
+template <typename TFrom, typename TTo>
+  struct is_convertible : etl::integral_constant<bool, __is_convertible_to(TFrom, TTo)> {};
+#else
   template <typename TFrom, typename TTo>
   struct is_convertible : etl::integral_constant<bool, (decltype(private_type_traits::returnable<TTo>(0))::value &&
                                                         decltype(private_type_traits::nonvoid_convertible<TFrom, TTo>(0))::value) ||
                                                         (etl::is_void<TFrom>::value && etl::is_void<TTo>::value)> {};
 #endif
+#endif
 
 #if ETL_CPP17_SUPPORTED
   template <typename TFrom, typename TTo >
diff --git a/include/etl/unordered_map.h b/include/etl/unordered_map.h
index 45220ad1..3d72a0ea 100644
--- a/include/etl/unordered_map.h
+++ b/include/etl/unordered_map.h
@@ -1306,7 +1306,7 @@ namespace etl
 
       return *this;
     }
-
+#if ETL_CPP11_SUPPORTED
     //*************************************************************************
     /// Move assignment operator.
     //*************************************************************************
@@ -1320,6 +1320,7 @@ namespace etl
 
       return *this;
     }
+#endif
 
   protected: