diff --git a/sol/function.hpp b/sol/function.hpp
index 8fd1a326..e9433732 100644
--- a/sol/function.hpp
+++ b/sol/function.hpp
@@ -80,12 +80,12 @@ public:
     }
 
     template<typename... Ret, typename... Args>
-    typename return_type<Ret...>::type operator()(types<Ret...>, Args&&... args) const {
+    ReturnType<Ret...> operator()(types<Ret...>, Args&&... args) const {
         return call<Ret...>(std::forward<Args>(args)...);
     }
 
     template<typename... Ret, typename... Args>
-    typename return_type<Ret...>::type call(Args&&... args) const {
+    ReturnType<Ret...> call(Args&&... args) const {
         push();
         int pushcount = stack::push_args(state(), std::forward<Args>(args)...);
         auto tr = types<Ret...>();
diff --git a/sol/state.hpp b/sol/state.hpp
index bb2d0080..befdeb0c 100644
--- a/sol/state.hpp
+++ b/sol/state.hpp
@@ -95,13 +95,13 @@ public:
                 luaL_requiref(L.get(), "package", luaopen_package, 1);
                 lua_pop(L.get(), 1);
                 break;
-            case lib::coroutine:
 #if SOL_LUA_VERSION > 501
+		  case lib::coroutine:
                 luaL_requiref(L.get(), "coroutine", luaopen_coroutine, 1);
                 lua_pop(L.get(), 1);
-#endif // Lua 5.2+ only
                 break;
-            case lib::string:
+#endif // Lua 5.2+ only
+		  case lib::string:
                 luaL_requiref(L.get(), "string", luaopen_string, 1);
                 lua_pop(L.get(), 1);
                 break;
diff --git a/sol/traits.hpp b/sol/traits.hpp
index 4e6478c8..2e9653a8 100644
--- a/sol/traits.hpp
+++ b/sol/traits.hpp
@@ -118,10 +118,13 @@ struct return_type<T> {
 };
 
 template<>
-struct return_type<> : types<>{
+struct return_type<> {
     typedef void type;
 };
 
+template <typename... Tn>
+using ReturnType = typename return_type<Tn...>::type;
+
 namespace detail {
 
 template<typename T, bool isclass = std::is_class<Unqualified<T>>::value>