diff --git a/endpoints/getting-started/openapi-appengine.yaml b/endpoints/getting-started/openapi-appengine.yaml
index a22beac89c2..f119a43c616 100644
--- a/endpoints/getting-started/openapi-appengine.yaml
+++ b/endpoints/getting-started/openapi-appengine.yaml
@@ -78,6 +78,7 @@ paths:
           google_id_token: []
 definitions:
   echoMessage:
+    type: "object"
     properties:
       message:
         type: "string"