diff --git a/app/serializers/api/customer_serializer.rb b/app/serializers/api/customer_serializer.rb
index ee543e5031..1c437a987e 100644
--- a/app/serializers/api/customer_serializer.rb
+++ b/app/serializers/api/customer_serializer.rb
@@ -1,6 +1,14 @@
 module Api
   class CustomerSerializer < ActiveModel::Serializer
-    attributes :id, :enterprise_id, :name, :code, :email, :allow_charges,
-               :gateway_recurring_payment_client_secret, :gateway_shop_id
+    attributes :id, :enterprise_id, :name, :code, :email, :allow_charges
+
+    def attributes
+      hash = super
+      if secret = object.gateway_recurring_payment_client_secret
+        hash.merge!(gateway_recurring_payment_client_secret: secret)
+      end
+      hash.merge!(gateway_shop_id: object.gateway_shop_id) if object.gateway_shop_id
+      hash
+    end
   end
 end