diff --git a/examples/tool/package.json b/examples/tool/package.json
index 534605a7..76ee4355 100644
--- a/examples/tool/package.json
+++ b/examples/tool/package.json
@@ -145,4 +145,4 @@
     "@universal-middleware/hono": "^0",
     "@universal-middleware/webroute": "^0"
   }
-}
+}
\ No newline at end of file
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 8fb1ee37..da654570 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -96,7 +96,7 @@ export interface UniversalMiddleware<
   ):
     | Awaitable<Response>
     | Awaitable<void>
-    | Awaitable<OutContext>
+    | Awaitable<OutContext | undefined>
     | ((response: Response) => Awaitable<Response>);
 }