diff --git a/include/boost/static_string/config.hpp b/include/boost/static_string/config.hpp
index c46ed57..7789e34 100644
--- a/include/boost/static_string/config.hpp
+++ b/include/boost/static_string/config.hpp
@@ -21,7 +21,7 @@
 // #define BOOST_STATIC_STRING_NULL_OPTIMIZATION
 
 // Can we have deduction guides?
-#ifdef __cpp_deduction_guides
+#if __cpp_deduction_guides >= 201703
 #define BOOST_STATIC_STRING_USE_DEDUCT
 #endif
 
@@ -36,7 +36,14 @@
 #define BOOST_STATIC_STRING_NODISCARD
 #endif
 
-#if __cplusplus > 201703L
+// MSVC doesn't define __cplusplus by default
+#ifdef _MSVC_LANG
+#define BOOST_STATIC_STRING_STANDARD_VERSION _MSVC_LANG
+#else
+#define BOOST_STATIC_STRING_STANDARD_VERSION __cplusplus
+#endif
+
+#if BOOST_STATIC_STRING_STANDARD_VERSION > 201703L
 #define BOOST_STATIC_STRING_CPP20_CONSTEXPR constexpr
 #define BOOST_STATIC_STRING_CPP17_CONSTEXPR constexpr
 #define BOOST_STATIC_STRING_CPP14_CONSTEXPR constexpr
@@ -46,7 +53,7 @@
 #define BOOST_STATIC_STRING_CPP14_CONSTEXPR_USED
 #define BOOST_STATIC_STRING_CPP11_CONSTEXPR_USED
 #define BOOST_STATIC_STRING_ALLOW_UNINIT_MEM
-#elif __cplusplus >= 201703L
+#elif BOOST_STATIC_STRING_STANDARD_VERSION >= 201703L
 #define BOOST_STATIC_STRING_CPP20_CONSTEXPR
 #define BOOST_STATIC_STRING_CPP17_CONSTEXPR constexpr
 #define BOOST_STATIC_STRING_CPP14_CONSTEXPR constexpr
@@ -54,7 +61,7 @@
 #define BOOST_STATIC_STRING_CPP17_CONSTEXPR_USED
 #define BOOST_STATIC_STRING_CPP14_CONSTEXPR_USED
 #define BOOST_STATIC_STRING_CPP11_CONSTEXPR_USED
-#elif __cplusplus >= 201402L
+#elif BOOST_STATIC_STRING_STANDARD_VERSION >= 201402L
 #define BOOST_STATIC_STRING_CPP20_CONSTEXPR
 #define BOOST_STATIC_STRING_CPP17_CONSTEXPR
 #define BOOST_STATIC_STRING_CPP14_CONSTEXPR constexpr
@@ -117,8 +124,8 @@
 #endif
 #endif
 
-#if (__cplusplus >= 201402L) && \
-(__cplusplus < 201703L) && \
+#if (BOOST_STATIC_STRING_STANDARD_VERSION >= 201402L) && \
+(BOOST_STATIC_STRING_STANDARD_VERSION < 201703L) && \
 defined(__clang__) && \
 ((__clang_major__ == 4) || (__clang_major__ == 5))
 // This directive works on clang
diff --git a/include/boost/static_string/detail/static_string.hpp b/include/boost/static_string/detail/static_string.hpp
index 8d335ce..f466f02 100644
--- a/include/boost/static_string/detail/static_string.hpp
+++ b/include/boost/static_string/detail/static_string.hpp
@@ -63,9 +63,16 @@ struct is_nothrow_convertible<From, To, typename std::enable_if<
     is_nothrow_convertible_msvc_helper<From, To>::value>::type>
         : std::true_type { };
 
-// void_t for c++11
+// GCC 4.8, 4.9 workaround for void_t to make the defining-type-id dependant 
 template<typename...>
-using void_t = void;
+struct void_t_helper
+{
+  using type = void;
+};
+
+// void_t for c++11
+template<typename... Ts>
+using void_t = typename void_t_helper<Ts...>::type;
 
 // Simplified check for if a type is an iterator
 template<class T, typename = void>
diff --git a/include/boost/static_string/impl/static_string.hpp b/include/boost/static_string/impl/static_string.hpp
index 5438bbb..be2b977 100644
--- a/include/boost/static_string/impl/static_string.hpp
+++ b/include/boost/static_string/impl/static_string.hpp
@@ -337,8 +337,8 @@ insert(
       count > max_size() - curr_size, std::length_error{"count() > max_size() - size()"});
   auto const index = pos - curr_data;
   Traits::move(&curr_data[index + count], &curr_data[index], curr_size - index);
-  this->set_size(curr_size + count);
   Traits::assign(&curr_data[index], count, ch);
+  this->set_size(curr_size + count);
   term();
   return &curr_data[index];
 }