diff --git a/questions/09155-hard-validdate/test-cases.ts b/questions/09155-hard-validdate/test-cases.ts
index a02fbb60..8e8db9c0 100644
--- a/questions/09155-hard-validdate/test-cases.ts
+++ b/questions/09155-hard-validdate/test-cases.ts
@@ -8,4 +8,7 @@ type cases = [
   Expect<Equal<ValidDate<'0100'>, false>>,
   Expect<Equal<ValidDate<'0132'>, false>>,
   Expect<Equal<ValidDate<'1301'>, false>>,
-]
+  Expect<Equal<ValidDate<'0123'>, true>>,
+  Expect<Equal<ValidDate<'01234'>, false>>,
+  Expect<Equal<ValidDate<''>, false>>,
+]