diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 257cdba5..79ab0b86 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -262,6 +262,15 @@ namespace WebSocketSharp
                  : null;
     }
 
+    internal static string CheckIfValidCloseParameters (this CloseStatusCode code, string reason)
+    {
+      return code.IsNoStatusCode () && !reason.IsNullOrEmpty ()
+             ? "NoStatusCode cannot have a reason."
+             : !reason.IsNullOrEmpty () && Encoding.UTF8.GetBytes (reason).Length > 123
+               ? "A reason has greater than the allowable max size."
+               : null;
+    }
+
     internal static string CheckIfValidCloseStatusCode (this ushort code)
     {
       return !code.IsCloseStatusCode ()