diff --git a/src/index.ts b/src/index.ts
index 996a168..a45676e 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -117,6 +117,10 @@ const KidShiftTaskCompleteIntentHandler = {
             return handlerInput.responseBuilder
                 .speak('Task completion failed')
                 .getResponse();
+        }).finally(() => {
+            return handlerInput.responseBuilder // ここに到達することはないはず
+                .speak('Task completion failed(UNKNOWN)')
+                .getResponse();
         });
     }
 };