diff --git a/cmdutils.c b/cmdutils.c
index d5095cec80..74829c96cf 100644
--- a/cmdutils.c
+++ b/cmdutils.c
@@ -99,7 +99,7 @@ unknown_opt:
             } else if (po->flags & OPT_INT) {
                 *po->u.int_arg = atoi(arg);
             } else if (po->flags & OPT_INT64) {
-                *po->u.int64_arg = atoll(arg);
+                *po->u.int64_arg = strtoll(arg, (char **)NULL, 10);
             } else if (po->flags & OPT_FLOAT) {
                 *po->u.float_arg = atof(arg);
             } else if (po->flags & OPT_FUNC2) {