diff --git a/app/controllers/api/web/push_subscriptions_controller.rb b/app/controllers/api/web/push_subscriptions_controller.rb
index 2711071b4a5..ced68d39fc7 100644
--- a/app/controllers/api/web/push_subscriptions_controller.rb
+++ b/app/controllers/api/web/push_subscriptions_controller.rb
@@ -49,7 +49,7 @@ class Api::Web::PushSubscriptionsController < Api::Web::BaseController
     {
       policy: 'all',
       alerts: Notification::TYPES.index_with { alerts_enabled },
-    }
+    }.deep_stringify_keys
   end
 
   def alerts_enabled