diff --git a/websocket-sharp/Net/WebHeaderCollection.cs b/websocket-sharp/Net/WebHeaderCollection.cs
index 1e5f49a6..66a69cfd 100644
--- a/websocket-sharp/Net/WebHeaderCollection.cs
+++ b/websocket-sharp/Net/WebHeaderCollection.cs
@@ -1875,7 +1875,7 @@ namespace WebSocketSharp.Net
       var headerType = getHeaderType (name);
 
       checkRestricted (name, headerType);
-      checkAllowed (name);
+      checkAllowed (headerType);
       set (name, value, headerType);
     }