diff --git a/README.md b/README.md
index bf79720..b449d96 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ WxPay.appid = 'YOUR_APPID'
 WxPay.key = 'YOUR_KEY'
 WxPay.mch_id = 'YOUR_MCH_ID'
 
-# cert, see https://pay.weixin.qq.com/wiki/doc/api/app.php?chapter=4_3
+# cert, see https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=4_3
 # using PCKS12
 WxPay.set_apiclient_by_pkcs12(File.read(pkcs12_filepath), pass)
 
--
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