diff --git a/reactos/lib/rtl/unicode.c b/reactos/lib/rtl/unicode.c
index 16eb6112791..2e73272a354 100644
--- a/reactos/lib/rtl/unicode.c
+++ b/reactos/lib/rtl/unicode.c
@@ -2545,7 +2545,7 @@ RtlFindCharInUnicodeString(
     Length = SearchString->Length / sizeof(WCHAR);
     if (Flags & RTL_FIND_CHAR_IN_UNICODE_STRING_START_AT_END)
     {
-        for (i = Length - 1; i >= 0; i--)
+        for (i = Length - 1; (SHORT)i >= 0; i--)
         {
             Found = RtlpIsCharInUnicodeString(SearchString->Buffer[i], MatchString, CaseInSensitive);
             if (Found == WantToFind)