diff --git a/include/ghc/fs_std.hpp b/include/ghc/fs_std.hpp
index 5dc3a8e..63231c5 100644
--- a/include/ghc/fs_std.hpp
+++ b/include/ghc/fs_std.hpp
@@ -51,6 +51,7 @@ using fstream = std::fstream;
 #endif
 #endif
 #ifndef GHC_USE_STD_FS
+#define GHC_WIN_WSTRING_STRING_TYPE
 #include <ghc/filesystem.hpp>
 namespace fs {
 using namespace ghc::filesystem;
diff --git a/include/ghc/fs_std_fwd.hpp b/include/ghc/fs_std_fwd.hpp
index f336a12..6d2ebfb 100644
--- a/include/ghc/fs_std_fwd.hpp
+++ b/include/ghc/fs_std_fwd.hpp
@@ -54,6 +54,7 @@ using fstream = std::fstream;
 #endif
 #endif
 #ifndef GHC_USE_STD_FS
+#define GHC_WIN_WSTRING_STRING_TYPE
 #define GHC_FILESYSTEM_FWD
 #include <ghc/filesystem.hpp>
 namespace fs {
diff --git a/include/ghc/fs_std_impl.hpp b/include/ghc/fs_std_impl.hpp
index a094993..005ec58 100644
--- a/include/ghc/fs_std_impl.hpp
+++ b/include/ghc/fs_std_impl.hpp
@@ -45,6 +45,7 @@
 #endif
 #endif
 #ifndef GHC_USE_STD_FS
+#define GHC_WIN_WSTRING_STRING_TYPE
 #define GHC_FILESYSTEM_IMPLEMENTATION
 #include <ghc/filesystem.hpp>
 #endif