diff --git a/dlls/msvcrt/mbcs.c b/dlls/msvcrt/mbcs.c
index 5d389bf3686..fe88cc7cadc 100644
--- a/dlls/msvcrt/mbcs.c
+++ b/dlls/msvcrt/mbcs.c
@@ -2253,6 +2253,17 @@ MSVCRT_size_t CDECL MSVCRT__mbstowcs_l(MSVCRT_wchar_t *wcstr, const char *mbstr,
     else
         locinfo = locale->locinfo;
 
+    if(!locinfo->lc_codepage) {
+        if(!wcstr)
+            return strlen(mbstr);
+
+        for(i=0; i<count; i++) {
+            wcstr[i] = (unsigned char)mbstr[i];
+            if(!wcstr[i]) break;
+        }
+        return i;
+    }
+
     /* Ignore count parameter */
     if(!wcstr)
         return MultiByteToWideChar(locinfo->lc_codepage, 0, mbstr, -1, NULL, 0)-1;