diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index a3284c42..dd3342fd 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -620,6 +620,11 @@ namespace WebSocketSharp
       return !code.IsReserved () || code.IsNoStatusCode ();
     }
 
+    internal static bool IsSendable (this CloseStatusCode code)
+    {
+      return !code.IsReserved () || code.IsNoStatusCode ();
+    }
+
     internal static bool IsText (this string value)
     {
       var len = value.Length;