diff --git a/dlls/msvcrt/dir.c b/dlls/msvcrt/dir.c
index 5e84e38a005..aaf2f8a4145 100644
--- a/dlls/msvcrt/dir.c
+++ b/dlls/msvcrt/dir.c
@@ -828,7 +828,7 @@ int CDECL MSVCRT__getdrive(void)
     WCHAR buffer[MAX_PATH];
     if (GetCurrentDirectoryW( MAX_PATH, buffer ) &&
         buffer[0] >= 'A' && buffer[0] <= 'z' && buffer[1] == ':')
-        return toupperW(buffer[0]) - 'A' + 1;
+        return MSVCRT_towupper(buffer[0]) - 'A' + 1;
     return 0;
 }
 
diff --git a/dlls/msvcrt/file.c b/dlls/msvcrt/file.c
index d20fa8e6a23..9c42aa56993 100644
--- a/dlls/msvcrt/file.c
+++ b/dlls/msvcrt/file.c
@@ -3166,7 +3166,7 @@ int CDECL MSVCRT__wstat64(const MSVCRT_wchar_t* path, struct MSVCRT__stat64 * bu
 
   /* FIXME: rdev isn't drive num, despite what the docs says-what is it? */
   if (MSVCRT_iswalpha(*path) && path[1] == ':')
-    buf->st_dev = buf->st_rdev = toupperW(*path) - 'A'; /* drive num */
+    buf->st_dev = buf->st_rdev = MSVCRT_towupper(*path) - 'A'; /* drive num */
   else
     buf->st_dev = buf->st_rdev = MSVCRT__getdrive() - 1;
 
diff --git a/dlls/msvcrt/msvcrt.h b/dlls/msvcrt/msvcrt.h
index 7c92abc4fda..4a13501993a 100644
--- a/dlls/msvcrt/msvcrt.h
+++ b/dlls/msvcrt/msvcrt.h
@@ -1200,6 +1200,7 @@ double parse_double(MSVCRT_wchar_t (*)(void*), void (*)(void*), void*, MSVCRT_pt
 int __cdecl MSVCRT_wcsncmp(const MSVCRT_wchar_t*, const MSVCRT_wchar_t*, MSVCRT_size_t);
 int __cdecl MSVCRT__wcsnicmp(const MSVCRT_wchar_t*, const MSVCRT_wchar_t*, MSVCRT_size_t);
 int __cdecl MSVCRT_towlower(MSVCRT_wint_t);
+int __cdecl MSVCRT_towupper(MSVCRT_wint_t);
 
 /* Maybe one day we'll enable the invalid parameter handlers with the full set of information (msvcrXXd)
  *      #define MSVCRT_INVALID_PMT(x) MSVCRT_call_invalid_parameter_handler(x, __FUNCTION__, __FILE__, __LINE__, 0)
diff --git a/dlls/msvcrt/wcs.c b/dlls/msvcrt/wcs.c
index 5f1d5f8e8c6..5188d4f8604 100644
--- a/dlls/msvcrt/wcs.c
+++ b/dlls/msvcrt/wcs.c
@@ -356,8 +356,7 @@ int CDECL MSVCRT__wcsupr_s_l( MSVCRT_wchar_t* str, MSVCRT_size_t n,
   while (n--)
   {
     if (!*ptr) return 0;
-    /* FIXME: add locale support */
-    *ptr = toupperW(*ptr);
+    *ptr = MSVCRT__towupper_l(*ptr, locale);
     ptr++;
   }