diff --git a/diff-no-index.c b/diff-no-index.c
index c554691df0..265709ba8c 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -198,7 +198,7 @@ void diff_no_index(struct rev_info *revs,
 			i++;
 		else {
 			j = diff_opt_parse(&revs->diffopt, argv + i, argc - i);
-			if (!j)
+			if (j <= 0)
 				die("invalid diff option/value: %s", argv[i]);
 			i += j;
 		}