diff --git a/dlls/wininet/internet.c b/dlls/wininet/internet.c
index 8a3340cdb0f..ac845a88764 100644
--- a/dlls/wininet/internet.c
+++ b/dlls/wininet/internet.c
@@ -1550,7 +1550,7 @@ BOOL WINAPI InternetCrackUrlW(LPCWSTR lpszUrl_orig, DWORD dwUrlLength_orig, DWOR
                     }
 
                     /* If the scheme is "file" and the host is just one letter, it's not a host */
-                    if(lpUC->nScheme==INTERNET_SCHEME_FILE && (lpszPort-lpszHost)==1)
+                    if(lpUC->nScheme==INTERNET_SCHEME_FILE && lpszPort <= lpszHost+1)
                     {
                         lpszcp=lpszHost;
                         SetUrlComponentValueW(&lpUC->lpszHostName, &lpUC->dwHostNameLength,