diff --git a/websocket-sharp/Net/WebHeaderCollection.cs b/websocket-sharp/Net/WebHeaderCollection.cs
index 71c52623..a41e7c6f 100644
--- a/websocket-sharp/Net/WebHeaderCollection.cs
+++ b/websocket-sharp/Net/WebHeaderCollection.cs
@@ -1346,7 +1346,7 @@ namespace WebSocketSharp.Net
     /// </exception>
     public override void Add (string name, string value)
     {
-      name = checkName (name);
+      name = checkName (name, "name");
       value = checkValue (value);
 
       var headerType = getHeaderType (name);