diff --git a/build/codeblocks/nana.cbp b/build/codeblocks/nana.cbp
index 188c964d..5beaa6f0 100644
--- a/build/codeblocks/nana.cbp
+++ b/build/codeblocks/nana.cbp
@@ -14,8 +14,8 @@
 				<Option compiler="gcc" />
 				<Option createDefFile="1" />
 				<Compiler>
-					<Add option="-std=c++11" />
 					<Add option="-Wall" />
+					<Add option="-std=c++11" />
 					<Add option="-g" />
 					<Add directory="../../include" />
 					<Add directory="../../extrlib/mingw" />
diff --git a/include/nana/filesystem/filesystem.hpp b/include/nana/filesystem/filesystem.hpp
index 86b907a6..36f8776d 100644
--- a/include/nana/filesystem/filesystem.hpp
+++ b/include/nana/filesystem/filesystem.hpp
@@ -561,22 +561,19 @@ namespace std {
 	}
 } // std
 #else
-
 //Implements the missing functions for various version of experimental/filesystem
-#	if defined(NANA_USING_STD_EXPERIMENTAL_FILESYSTEM)
 	namespace std
 	{
 		namespace filesystem
 		{
 			//Visual Studio 2017
-			#if (defined(_MSC_VER) && (_MSC_VER > 1912)) ||	\
-				(!defined(__clang__) && defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 801))
+#if			(defined(NANA_USING_STD_EXPERIMENTAL_FILESYSTEM) && defined(_MSC_VER) && (_MSC_VER > 1912)) ||	\
+				(!defined(__clang__) && defined(__GNUC__) && (__cplusplus < 201603))
 			path weakly_canonical(const path& p);
 			path weakly_canonical(const path& p, std::error_code& err);
-			#endif
+#endif
 		}
 	}
-#	endif
 
 #endif	//NANA_USING_NANA_FILESYSTEM
 
diff --git a/source/filesystem/filesystem.cpp b/source/filesystem/filesystem.cpp
index 9180f084..ae812104 100644
--- a/source/filesystem/filesystem.cpp
+++ b/source/filesystem/filesystem.cpp
@@ -1399,16 +1399,15 @@ namespace std
 	}//end namespace filesystem
 }//end namespace std
 
-#else 	//NANA_USING_NANA_FILESYSTEM
-#	if defined(NANA_USING_STD_EXPERIMENTAL_FILESYSTEM)
+#else 	//else NANA_USING_NANA_FILESYSTEM
 
 	//Defines the functions that are not provided by experimental/filesystem
 	namespace std
 	{
 		namespace filesystem
 		{
-			#if (defined(_MSC_VER) && (_MSC_VER > 1912)) || \
-				(!defined(__clang__) && defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 801))
+#if		(defined(NANA_USING_STD_EXPERIMENTAL_FILESYSTEM) && defined(_MSC_VER) && (_MSC_VER > 1912)) ||	\
+			(!defined(__clang__) && defined(__GNUC__) && (__cplusplus < 201603))
 
 			namespace detail
 			{
@@ -1551,10 +1550,9 @@ namespace std
 			{
 				return weakly_canonical(p, &err);
 			}
-			#endif
+#endif
 		}
 	}
-#	endif
 
 #endif //NANA_USING_NANA_FILESYSTEM