diff --git a/api/client-server/third_party_lookup.yaml b/api/client-server/third_party_lookup.yaml
index 86389603..848d92d1 100644
--- a/api/client-server/third_party_lookup.yaml
+++ b/api/client-server/third_party_lookup.yaml
@@ -129,7 +129,8 @@ paths:
       responses:
         200:
           description: The Matrix User IDs found with the given parameters.
-          $ref: ../application-service/definitions/schema/user_batch.yaml
+          schema:
+            $ref: ../application-service/definitions/schema/user_batch.yaml
         404:
           description: The Matrix User ID was not found
           examples: