diff --git a/reactos/lib/sdk/crt/string/strtoull.c b/reactos/lib/sdk/crt/string/strtoull.c
index b3f4b476114..edd4fd14c67 100644
--- a/reactos/lib/sdk/crt/string/strtoull.c
+++ b/reactos/lib/sdk/crt/string/strtoull.c
@@ -54,6 +54,7 @@ strtoull(const char *nptr, char **endptr, int base)
   if (any < 0)
   {
     acc = ULLONG_MAX;
+    __set_errno(ERANGE);
   }
   else if (neg)
     acc = -acc;