diff --git a/Include/auROXTL/auTemplateMeta.hpp b/Include/auROXTL/auTemplateMeta.hpp
index eb0a8707..35a2c20f 100644
--- a/Include/auROXTL/auTemplateMeta.hpp
+++ b/Include/auROXTL/auTemplateMeta.hpp
@@ -48,7 +48,7 @@ inline constexpr bool AuIsSame_v = AuIsSame<T, U>::value;
 namespace _audetail
 {
     template <class T>
-    AuBoolType<!std::is_union<T>::value> IsClass(int T:: *);
+    AuBoolType<!__is_union(T)> IsClass(int T:: *);
 
     template <class>
     AuFalseType IsClass(...);
@@ -232,13 +232,16 @@ struct AuAddRReference
 template <class T>
 using AuAddRReference_t = typename AuAddRReference<T>::type;
 
+template <class T>
+inline AuAddRReference_t<T> AuDeclVal();
+
 template <bool Test, class T = void>
 using AuEnableIf_t = typename AuEnableIf<Test, T>::type;
 
 template <class T, class ... Args>
 struct AuIsConstructible
 {
-    template <class T, class ... Args> static constexpr AuTrueType  Test(decltype(T(std::declval<Args>()...)));
+    template <class T, class ... Args> static constexpr AuTrueType  Test(decltype(T(AuDeclVal<Args>()...)));
     template <class T, class ... Args> static constexpr AuFalseType Test(...);
     using type = decltype(Test<T, Args...>(0));
 };
@@ -270,7 +273,7 @@ struct AuIsBaseOfTemplateImpl
     template <class... Ts>
     static constexpr AuTrueType  Test(const Base<Ts...> *);
     static constexpr AuFalseType Test(...);
-    using type = decltype(Test(std::declval<AuRemoveReference_t<Derived> *>()));
+    using type = decltype(Test(AuDeclVal<AuRemoveReference_t<Derived> *>()));
 };
 
 template <template <class...> class Base, typename Derived>