diff --git a/Unity3D/PocoManager.cs b/Unity3D/PocoManager.cs
index c2c46f8..01398f5 100644
--- a/Unity3D/PocoManager.cs
+++ b/Unity3D/PocoManager.cs
@@ -152,7 +152,11 @@ private object GetScreenSize(List<object> param)
     public void stopListening()
     {
         mRunning = false;
-        server?.Stop();
+        var server = this.server;
+        if (server != null)
+        {
+            server.Stop();
+        }
     }
 
     [RPC]