diff --git a/include/nana/filesystem/filesystem.hpp b/include/nana/filesystem/filesystem.hpp
index 1bbe3aa9..b7cb9cdc 100644
--- a/include/nana/filesystem/filesystem.hpp
+++ b/include/nana/filesystem/filesystem.hpp
@@ -112,7 +112,7 @@ namespace nana  { namespace experimental { namespace filesystem
 	public:
 #if defined(NANA_WINDOWS)
 		using value_type = wchar_t;
-		const static value_type preferred_separator = '\\';  //? L'\\' ?
+		const static value_type preferred_separator = L'\\';  //? L'\\' ?
 #else
 		using value_type = char;
 		const static value_type preferred_separator = '/';
@@ -151,10 +151,10 @@ namespace nana  { namespace experimental { namespace filesystem
 		//bool has_root_directory() const;
 		//bool has_root_path() const;
 		//bool has_relative_path() const;
-		bool has_parent_path() const { return !parent_path().empty(); };   // temp;;
-		bool has_filename() const    { return !filename().empty(); };   // temp;
+		bool has_parent_path() const { return !parent_path().string().empty(); };   // temp;;
+		bool has_filename() const    { return !filename().string().empty(); };   // temp;
 		//bool has_stem() const;
-		bool has_extension() const   { return !extension().empty(); };   // temp
+		bool has_extension() const   { return !extension().string().empty(); };   // temp
 		//bool is_absolute() const;
 		//bool is_relative() const;
 
diff --git a/source/filesystem/filesystem.cpp b/source/filesystem/filesystem.cpp
index 1f523f3a..ead15a1a 100644
--- a/source/filesystem/filesystem.cpp
+++ b/source/filesystem/filesystem.cpp
@@ -110,6 +110,7 @@ namespace nana {	namespace experimental {	namespace filesystem
 			return pathstr_.compare(p.pathstr_);
 		}
 
+		/// true if the path is empty, false otherwise. ??
 		bool path::empty() const noexcept
 		{
 #if defined(NANA_WINDOWS)
@@ -122,17 +123,20 @@ namespace nana {	namespace experimental {	namespace filesystem
 
 		path path::extension() const
 		{
+			// todo: make more globlal
 #if defined(NANA_WINDOWS)
-			auto pos = pathstr_.find_last_of(L"\\/.");
+            auto SLorP=L"\\/.";
+			auto P=L'.';
 #else
-			auto pos = pathstr_.find_last_of("\\/.");
+			auto SLorP="\\/.";
+			auto P='.';
 #endif
-			if ((pos == pathstr_.npos) || (pathstr_[pos] != '.'))
-				return path();
+			auto pos = pathstr_.find_last_of(SLorP);
 
-				
-			if (pos + 1 == pathstr_.size())
-				return path();
+			if (    ( pos == pathstr_.npos)
+				 || ( pathstr_[pos] != P )
+				 || ( pos + 1 == pathstr_.size()  ))
+			   return path();
 
 			return path(pathstr_.substr(pos));
 		}