diff --git a/include/wx/filefn.h b/include/wx/filefn.h
index a0fd19d272..537d889e88 100644
--- a/include/wx/filefn.h
+++ b/include/wx/filefn.h
@@ -66,7 +66,8 @@ WXDLLEXPORT_DATA(extern const wxChar*) wxEmptyString;
 // ----------------------------------------------------------------------------
 
 // Microsoft compiler loves underscores, feed them to it
-#if defined( __VISUALC__ ) || wxCHECK_W32API_VERSION( 0, 5 ) \
+#if defined( __VISUALC__ ) \
+    || ( defined(__MINGW32__) && wxCHECK_W32API_VERSION( 0, 5 ) ) \
     || ( defined(__MWERKS__) && defined(__WXMSW__) )
     // functions
     #define   wxClose      _close
diff --git a/include/wx/wxchar.h b/include/wx/wxchar.h
index c4742c529f..072e4cdf28 100644
--- a/include/wx/wxchar.h
+++ b/include/wx/wxchar.h
@@ -63,7 +63,7 @@
         #define wxHAVE_TCHAR_FUNCTIONS
     #elif defined(__BORLANDC__) && (__BORLANDC__ >= 0x520)
         #define wxHAVE_TCHAR_FUNCTIONS
-    #elif defined(__GNUWIN32__) && wxCHECK_W32API_VERSION( 1, 0 )
+    #elif defined(__MINGW32__) && wxCHECK_W32API_VERSION( 1, 0 )
         #define wxHAVE_TCHAR_FUNCTIONS
         #include <stddef.h>
         #include <string.h>