diff --git a/docs/concepts/stacks.md b/docs/concepts/stacks.md
index c5f9be0a..e7084d72 100644
--- a/docs/concepts/stacks.md
+++ b/docs/concepts/stacks.md
@@ -33,6 +33,7 @@ app.get('/hello', (c) => {
     message: `Hello!`,
   })
 })
+export default app
 ```
 
 ## Validation with Zod