diff --git a/lib/rpc-client/client.js b/lib/rpc-client/client.js
index 25f7570..f5686ee 100644
--- a/lib/rpc-client/client.js
+++ b/lib/rpc-client/client.js
@@ -174,7 +174,7 @@ pro.rpcInvoke = function(serverId, msg, cb) {
     cb(new Error('[pomelo-rpc] fail to do rpc invoke for client is not running'));
     return;
   }
-  this._station.dispatch(tracer, serverId, msg, null, cb);
+  this._station.dispatch(tracer, serverId, msg, {}, cb);
 };
 
 pro.before = function(filter) {