diff --git a/wechatpayv3/marketing.py b/wechatpayv3/marketing.py
index 6d36767..4457cc9 100644
--- a/wechatpayv3/marketing.py
+++ b/wechatpayv3/marketing.py
@@ -280,7 +280,7 @@ def marketing_favor_stock_create(self,
     else:
         raise Exception('stock_type is not assigned.')
     if out_request_no:
-        params.update({out_request_no: out_request_no})
+        params.update({'out_request_no': out_request_no})
     else:
         raise Exception('out_request_no is not assigned.')
     if no_cash: