diff --git a/builtin-merge.c b/builtin-merge.c
index e95c5dc71746fb6f4e87913669701a2f65070602..e5cf795307a62ea37c2ab4fe39f801cb5a680f03 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -792,7 +792,7 @@ static int suggest_conflicts(void)
 static struct commit *is_old_style_invocation(int argc, const char **argv)
 {
 	struct commit *second_token = NULL;
-	if (argc > 1) {
+	if (argc > 2) {
 		unsigned char second_sha1[20];
 
 		if (get_sha1(argv[1], second_sha1))