diff --git a/builtin-fetch.c b/builtin-fetch.c
index a11548c894..5841b3e51a 100644
--- a/builtin-fetch.c
+++ b/builtin-fetch.c
@@ -637,6 +637,8 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 			if (!strcmp(argv[i], "tag")) {
 				char *ref;
 				i++;
+				if (i >= argc)
+					die("You need to specify a tag name.");
 				ref = xmalloc(strlen(argv[i]) * 2 + 22);
 				strcpy(ref, "refs/tags/");
 				strcat(ref, argv[i]);