diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 589410ad..9e7a5538 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -197,6 +197,13 @@ namespace WebSocketSharp
              : stream.ToByteArray ();
     }
 
+    internal static bool Contains (
+      this NameValueCollection collection, string name
+    )
+    {
+      return collection[name] != null;
+    }
+
     internal static bool Contains (
       this NameValueCollection collection,
       string name,
@@ -1099,25 +1106,6 @@ namespace WebSocketSharp
                : value.IndexOfAny (chars) > -1;
     }
 
-    /// <summary>
-    /// Determines whether the specified <see cref="NameValueCollection"/> contains
-    /// the entry with the specified <paramref name="name"/>.
-    /// </summary>
-    /// <returns>
-    /// <c>true</c> if <paramref name="collection"/> contains the entry with
-    /// <paramref name="name"/>; otherwise, <c>false</c>.
-    /// </returns>
-    /// <param name="collection">
-    /// A <see cref="NameValueCollection"/> to test.
-    /// </param>
-    /// <param name="name">
-    /// A <see cref="string"/> that represents the key of the entry to find.
-    /// </param>
-    public static bool Contains (this NameValueCollection collection, string name)
-    {
-      return collection != null && collection.Count > 0 ? collection[name] != null : false;
-    }
-
     /// <summary>
     /// Emits the specified <see cref="EventHandler"/> delegate if it isn't <see langword="null"/>.
     /// </summary>