diff --git a/builtin-pack-refs.c b/builtin-pack-refs.c
index 246dd6372e..db57fee72d 100644
--- a/builtin-pack-refs.c
+++ b/builtin-pack-refs.c
@@ -56,7 +56,7 @@ static void prune_ref(struct ref_to_prune *r)
 	struct ref_lock *lock = lock_ref_sha1(r->name + 5, r->sha1, 1);
 
 	if (lock) {
-		unlink(git_path(r->name));
+		unlink(git_path("%s", r->name));
 		unlock_ref(lock);
 	}
 }