diff --git a/parallel_hashmap/phmap_base.h b/parallel_hashmap/phmap_base.h
index 0b6674a..8be4e0e 100644
--- a/parallel_hashmap/phmap_base.h
+++ b/parallel_hashmap/phmap_base.h
@@ -329,10 +329,10 @@ template <typename T>
 using underlying_type_t = typename std::underlying_type<T>::type;
 
 template< class F, class... ArgTypes>
-#if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
-using invoke_result_t = typename std::invoke_result_t<F, ArgTypes...>;
+#ifdef PHMAP_HAVE_CC17
+    using invoke_result_t = typename std::invoke_result_t<F, ArgTypes...>;
 #else
-using invoke_result_t = typename std::result_of<F(ArgTypes...)>::type;
+    using invoke_result_t = typename std::result_of<F(ArgTypes...)>::type;
 #endif
 
 namespace type_traits_internal {
diff --git a/parallel_hashmap/phmap_config.h b/parallel_hashmap/phmap_config.h
index dd5a0bf..5e527cc 100644
--- a/parallel_hashmap/phmap_config.h
+++ b/parallel_hashmap/phmap_config.h
@@ -109,6 +109,7 @@
 #endif
 
 
+
 // -----------------------------------------------------------------------------
 // Compiler Feature Checks
 // -----------------------------------------------------------------------------
@@ -119,6 +120,12 @@
     #define PHMAP_HAVE_BUILTIN(x) 0
 #endif
 
+#if (defined(_MSVC_LANG) && _MSVC_LANG >= 201703) || __cplusplus >= 201703
+    #define PHMAP_HAVE_CC17 1
+#else
+    #define PHMAP_HAVE_CC17 0
+#endif
+
 // ----------------------------------------------------------------
 // Checks whether `std::is_trivially_destructible<T>` is supported.
 // ----------------------------------------------------------------
@@ -304,8 +311,7 @@
 
 // #pragma message(PHMAP_VAR_NAME_VALUE(_MSVC_LANG))
 
-#if defined(_MSC_VER) && _MSC_VER >= 1910 && \
-    ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703) || __cplusplus >= 201703)
+#if defined(_MSC_VER) && _MSC_VER >= 1910 && PHMAP_HAVE_CC17
     // #define PHMAP_HAVE_STD_ANY 1
     #define PHMAP_HAVE_STD_OPTIONAL 1
     #define PHMAP_HAVE_STD_VARIANT 1
@@ -314,7 +320,7 @@
     #endif
 #endif
 
-#if (defined(_MSVC_LANG) && _MSVC_LANG >= 201703) || __cplusplus >= 201703
+#if PHMAP_HAVE_CC17
     #define PHMAP_HAVE_SHARED_MUTEX 1
 #endif
 
@@ -633,7 +639,7 @@
 // ----------------------------------------------------------------------
 // constexpr if
 // ----------------------------------------------------------------------
-#if __cplusplus >= 201703 || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703)
+#if PHMAP_HAVE_CC17
     #define PHMAP_IF_CONSTEXPR(expr) if constexpr ((expr))
 #else 
     #define PHMAP_IF_CONSTEXPR(expr) if ((expr))