diff --git a/shadowsocks-csharp/Controller/GfwListUpdater.cs b/shadowsocks-csharp/Controller/GfwListUpdater.cs
index 77be9c03..4cf77293 100644
--- a/shadowsocks-csharp/Controller/GfwListUpdater.cs
+++ b/shadowsocks-csharp/Controller/GfwListUpdater.cs
@@ -16,10 +16,20 @@ namespace Shadowsocks.Controller
 
         private static string PAC_FILE = PACServer.PAC_FILE;
 
-        public event EventHandler UpdateCompleted;
+        public event EventHandler<ResultEventArgs> UpdateCompleted;
 
         public event ErrorEventHandler Error;
 
+        public class ResultEventArgs : EventArgs
+        {
+            public bool Success;
+
+            public ResultEventArgs(bool success)
+            {
+                this.Success = success;
+            }
+        }
+
         private void http_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
         {
             try
@@ -28,10 +38,19 @@ namespace Shadowsocks.Controller
 
                 string abpContent = Utils.UnGzip(Resources.abp_js);
                 abpContent = abpContent.Replace("__RULES__", SimpleJson.SimpleJson.SerializeObject(lines));
+                if (File.Exists(PAC_FILE))
+                {
+                    string original = File.ReadAllText(PAC_FILE, Encoding.UTF8);
+                    if (original == abpContent)
+                    {
+                        UpdateCompleted(this, new ResultEventArgs(false));
+                        return;
+                    }
+                }
                 File.WriteAllText(PAC_FILE, abpContent, Encoding.UTF8);
                 if (UpdateCompleted != null)
                 {
-                    UpdateCompleted(this, new EventArgs());
+                    UpdateCompleted(this, new ResultEventArgs(true));
                 }
             }
             catch (Exception ex)
diff --git a/shadowsocks-csharp/Controller/ShadowsocksController.cs b/shadowsocks-csharp/Controller/ShadowsocksController.cs
index 4e343c96..203417c2 100755
--- a/shadowsocks-csharp/Controller/ShadowsocksController.cs
+++ b/shadowsocks-csharp/Controller/ShadowsocksController.cs
@@ -39,7 +39,7 @@ namespace Shadowsocks.Controller
         // when user clicked Edit PAC, and PAC file has already created
         public event EventHandler<PathEventArgs> PACFileReadyToOpen;
 
-        public event EventHandler UpdatePACFromGFWListCompleted;
+        public event EventHandler<GFWListUpdater.ResultEventArgs> UpdatePACFromGFWListCompleted;
 
         public event ErrorEventHandler UpdatePACFromGFWListError;
 
@@ -282,7 +282,7 @@ namespace Shadowsocks.Controller
             UpdateSystemProxy();
         }
 
-        private void pacServer_PACUpdateCompleted(object sender, EventArgs e)
+        private void pacServer_PACUpdateCompleted(object sender, GFWListUpdater.ResultEventArgs e)
         {
             if (UpdatePACFromGFWListCompleted != null)
                 UpdatePACFromGFWListCompleted(this, e);
diff --git a/shadowsocks-csharp/Data/cn.txt b/shadowsocks-csharp/Data/cn.txt
index 51ac217d..f398b048 100644
--- a/shadowsocks-csharp/Data/cn.txt
+++ b/shadowsocks-csharp/Data/cn.txt
@@ -43,6 +43,7 @@ System Proxy Disabled=系统代理未启用
 Update PAC from GFWList=从 GFWList 更新 PAC
 Failed to update PAC file =更新 PAC 文件失败
 PAC updated=更新 PAC 成功
+No updates found. Please report to GFWList if you have problems with it.=未发现更新。如有问题请提交给 GFWList。
 No QRCode found. Try to zoom in or move it to the center of the screen.=找不到二维码，尝试把它放大或者移动到靠近屏幕中间的位置
 Failed to decode QRCode=无法解析二维码
 Failed to update registry=无法修改注册表
diff --git a/shadowsocks-csharp/View/MenuViewController.cs b/shadowsocks-csharp/View/MenuViewController.cs
index 6b897603..9fe9fcd3 100755
--- a/shadowsocks-csharp/View/MenuViewController.cs
+++ b/shadowsocks-csharp/View/MenuViewController.cs
@@ -207,9 +207,10 @@ namespace Shadowsocks.View
             Logging.LogUsefulException(e.GetException());
         }
 
-        void controller_UpdatePACFromGFWListCompleted(object sender, EventArgs e)
+        void controller_UpdatePACFromGFWListCompleted(object sender, GFWListUpdater.ResultEventArgs e)
         {
-            ShowBalloonTip(I18N.GetString("Shadowsocks"), I18N.GetString("PAC updated"), ToolTipIcon.Info, 1000);
+            string result = e.Success ? I18N.GetString("PAC updated") : I18N.GetString("No updates found. Please report to GFWList if you have problems with it.");
+            ShowBalloonTip(I18N.GetString("Shadowsocks"), result, ToolTipIcon.Info, 1000);
         }
 
         void updateChecker_NewVersionFound(object sender, EventArgs e)