diff --git a/websocket-sharp/Net/HttpResponseHeader.cs b/websocket-sharp/Net/HttpResponseHeader.cs
new file mode 100644
index 00000000..954517ef
--- /dev/null
+++ b/websocket-sharp/Net/HttpResponseHeader.cs
@@ -0,0 +1,172 @@
+#region License
+/*
+ * HttpResponseHeader.cs
+ *
+ * This code is derived from System.Net.HttpResponseHeader.cs of Mono
+ * (http://www.mono-project.com).
+ *
+ * The MIT License
+ *
+ * Copyright (c) 2005 Novell, Inc. (http://www.novell.com)
+ * Copyright (c) 2014 sta.blockhead
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#endregion
+
+#region Authors
+/*
+ * Authors:
+ * - Gonzalo Paniagua Javier <gonzalo@novell.com>
+ */
+#endregion
+
+namespace WebSocketSharp.Net
+{
+  /// <summary>
+  /// Contains the HTTP headers that can be specified in a server response.
+  /// </summary>
+  /// <remarks>
+  /// The HttpResponseHeader enumeration contains the HTTP response headers defined in
+  /// <see href="http://tools.ietf.org/html/rfc2616#section-14">RFC 2616</see> for HTTP/1.1.
+  /// </remarks>
+  public enum HttpResponseHeader
+  {
+    /// <summary>
+    /// Indicates the Cache-Control header.
+    /// </summary>
+    CacheControl,
+    /// <summary>
+    /// Indicates the Connection header.
+    /// </summary>
+    Connection,
+    /// <summary>
+    /// Indicates the Date header.
+    /// </summary>
+    Date,
+    /// <summary>
+    /// Indicates the Keep-Alive header.
+    /// </summary>
+    KeepAlive,
+    /// <summary>
+    /// Indicates the Pragma header.
+    /// </summary>
+    Pragma,
+    /// <summary>
+    /// Indicates the Trailer header.
+    /// </summary>
+    Trailer,
+    /// <summary>
+    /// Indicates the Transfer-Encoding header.
+    /// </summary>
+    TransferEncoding,
+    /// <summary>
+    /// Indicates the Upgrade header.
+    /// </summary>
+    Upgrade,
+    /// <summary>
+    /// Indicates the Via header.
+    /// </summary>
+    Via,
+    /// <summary>
+    /// Indicates the Warning header.
+    /// </summary>
+    Warning,
+    /// <summary>
+    /// Indicates the Allow header.
+    /// </summary>
+    Allow,
+    /// <summary>
+    /// Indicates the Content-Length header.
+    /// </summary>
+    ContentLength,
+    /// <summary>
+    /// Indicates the Content-Type header.
+    /// </summary>
+    ContentType,
+    /// <summary>
+    /// Indicates the Content-Encoding header.
+    /// </summary>
+    ContentEncoding,
+    /// <summary>
+    /// Indicates the Content-Language header.
+    /// </summary>
+    ContentLanguage,
+    /// <summary>
+    /// Indicates the Content-Location header.
+    /// </summary>
+    ContentLocation,
+    /// <summary>
+    /// Indicates the Content-MD5 header.
+    /// </summary>
+    ContentMd5,
+    /// <summary>
+    /// Indicates the Content-Range header.
+    /// </summary>
+    ContentRange,
+    /// <summary>
+    /// Indicates the Expires header.
+    /// </summary>
+    Expires,
+    /// <summary>
+    /// Indicates the Last-Modified header.
+    /// </summary>
+    LastModified,
+    /// <summary>
+    /// Indicates the Accept-Ranges header.
+    /// </summary>
+    AcceptRanges,
+    /// <summary>
+    /// Indicates the Age header.
+    /// </summary>
+    Age,
+    /// <summary>
+    /// Indicates the ETag header.
+    /// </summary>
+    ETag,
+    /// <summary>
+    /// Indicates the Location header.
+    /// </summary>
+    Location,
+    /// <summary>
+    /// Indicates the Proxy-Authenticate header.
+    /// </summary>
+    ProxyAuthenticate,
+    /// <summary>
+    /// Indicates the Retry-After header.
+    /// </summary>
+    RetryAfter,
+    /// <summary>
+    /// Indicates the Server header.
+    /// </summary>
+    Server,
+    /// <summary>
+    /// Indicates the Set-Cookie header.
+    /// </summary>
+    SetCookie,
+    /// <summary>
+    /// Indicates the Vary header.
+    /// </summary>
+    Vary,
+    /// <summary>
+    /// Indicates the WWW-Authenticate header.
+    /// </summary>
+    WwwAuthenticate
+  }
+}
diff --git a/websocket-sharp/Net/WebHeaderCollection.cs b/websocket-sharp/Net/WebHeaderCollection.cs
index 335d77a2..69bf4c8b 100644
--- a/websocket-sharp/Net/WebHeaderCollection.cs
+++ b/websocket-sharp/Net/WebHeaderCollection.cs
@@ -44,7 +44,6 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
-using System.Net;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
 using System.Security.Permissions;
diff --git a/websocket-sharp/websocket-sharp.csproj b/websocket-sharp/websocket-sharp.csproj
index 5cc7c55e..c1192aaa 100644
--- a/websocket-sharp/websocket-sharp.csproj
+++ b/websocket-sharp/websocket-sharp.csproj
@@ -138,6 +138,7 @@
     <Compile Include="Net\SslConfiguration.cs" />
     <Compile Include="Net\HttpListenerAsyncResult.cs" />
     <Compile Include="Net\HttpRequestHeader.cs" />
+    <Compile Include="Net\HttpResponseHeader.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>