diff --git a/Rpc/Service.php b/Rpc/Service.php
index 637d2060..8bf2a2b9 100644
--- a/Rpc/Service.php
+++ b/Rpc/Service.php
@@ -94,8 +94,7 @@ class Service extends Component
 	 */
 	public static function replace(Request $request, array $service): Request
 	{
-		$body = $request->params->getBodyAndClear();
-		if (is_null($serialize = Json::decode($body))) {
+		if (!is_array($body = $request->params->getBodyAndClear())) {
 			throw new Exception('Protocol format error.');
 		}
 		if (!isset($serialize['cmd'])) {