diff --git a/wchat/wx/Recharge.php b/wchat/wx/Recharge.php
index f719352..243aa37 100644
--- a/wchat/wx/Recharge.php
+++ b/wchat/wx/Recharge.php
@@ -116,8 +116,8 @@ class Recharge extends SmallProgram
 		$key = $this->config->getKey();
 		$sign_type = $this->config->getSignType();
 
-		$data['sign_type'] = $sign_type;
 		$data['sign'] = Help::sign($data, $key, $sign_type);
+		$data['sign_type'] = $sign_type;
 
 		return Help::toXml($data);
 	}