diff --git a/questions/00008-medium-readonly-2/test-cases.ts b/questions/00008-medium-readonly-2/test-cases.ts
index 8fb942ea3..92db4df43 100644
--- a/questions/00008-medium-readonly-2/test-cases.ts
+++ b/questions/00008-medium-readonly-2/test-cases.ts
@@ -6,6 +6,9 @@ type cases = [
   Expect<Alike<MyReadonly2<Todo2, 'title' | 'description'>, Expected>>,
 ]
 
+// @ts-expect-error
+type error = MyReadonly2<Todo1, 'title' | 'invalid'>
+
 interface Todo1 {
   title: string
   description?: string