diff --git a/dlls/msvcrt/wcs.c b/dlls/msvcrt/wcs.c
index 3e5bb512ff6..1ae292423c0 100644
--- a/dlls/msvcrt/wcs.c
+++ b/dlls/msvcrt/wcs.c
@@ -2487,7 +2487,7 @@ unsigned __int64 CDECL MSVCRT__wcstoui64(const MSVCRT_wchar_t *nptr,
 MSVCRT_ulong __cdecl MSVCRT__wcstoul_l(const MSVCRT_wchar_t *s,
         MSVCRT_wchar_t **end, int base, MSVCRT__locale_t locale)
 {
-    __int64 ret = MSVCRT__wcstoui64_l(s, end, base, locale);
+    unsigned __int64 ret = MSVCRT__wcstoui64_l(s, end, base, locale);
 
     if(ret > MSVCRT_ULONG_MAX) {
         ret = MSVCRT_ULONG_MAX;