diff --git a/websocket-sharp/Net/WebHeaderCollection.cs b/websocket-sharp/Net/WebHeaderCollection.cs
index a41e7c6f..4a7e518b 100644
--- a/websocket-sharp/Net/WebHeaderCollection.cs
+++ b/websocket-sharp/Net/WebHeaderCollection.cs
@@ -1347,7 +1347,7 @@ namespace WebSocketSharp.Net
     public override void Add (string name, string value)
     {
       name = checkName (name, "name");
-      value = checkValue (value);
+      value = checkValue (value, "value");
 
       var headerType = getHeaderType (name);