diff --git a/wchat/wx/V3/WxV3PaymentTait.php b/wchat/wx/V3/WxV3PaymentTait.php
index eb1833a..8275b27 100644
--- a/wchat/wx/V3/WxV3PaymentTait.php
+++ b/wchat/wx/V3/WxV3PaymentTait.php
@@ -39,9 +39,11 @@ trait WxV3PaymentTait
      */
     public function signature(string $http_method, string $canonical_url, string $body = ''): string
     {
-        $rand = md5(random_bytes(32));
-        $time = time();
-        $message = sprintf("%s\n%s\n%d\n%s\n[]\n", $http_method, $canonical_url, $time, $rand);
+        $rand    = md5(random_bytes(32));
+        $time    = time();
+
+        var_dump($body);
+        $message = sprintf("%s\n%s\n%d\n%s\n%s\n", $http_method, $canonical_url, $time, $rand, $body);
 
         $sign = $this->openssl_signature($message);