diff --git a/data/api/client-server/receipts.yaml b/data/api/client-server/receipts.yaml
index 27825001..0b8d4593 100644
--- a/data/api/client-server/receipts.yaml
+++ b/data/api/client-server/receipts.yaml
@@ -93,7 +93,8 @@ paths:
             application/json: {
               }
           schema:
-            type: object  # empty json object
+            type: object
+            maxProperties: 0  # empty json object
         429:
           description: This request was rate-limited.
           schema: