diff --git a/v2rayN/v2rayN/Forms/AddServer3Form.cs b/v2rayN/v2rayN/Forms/AddServer3Form.cs
index c39f2cfe..78192e45 100644
--- a/v2rayN/v2rayN/Forms/AddServer3Form.cs
+++ b/v2rayN/v2rayN/Forms/AddServer3Form.cs
@@ -121,8 +121,7 @@ namespace v2rayN.Forms
         {
             ClearServer();
 
-            string msg;
-            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out msg);
+            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out string msg);
             if (vmessItem == null)
             {
                 UI.Show(msg);
diff --git a/v2rayN/v2rayN/Forms/AddServer4Form.cs b/v2rayN/v2rayN/Forms/AddServer4Form.cs
index d331bec2..6adad2c1 100644
--- a/v2rayN/v2rayN/Forms/AddServer4Form.cs
+++ b/v2rayN/v2rayN/Forms/AddServer4Form.cs
@@ -110,8 +110,7 @@ namespace v2rayN.Forms
         {
             ClearServer();
 
-            string msg;
-            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out msg);
+            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out string msg);
             if (vmessItem == null)
             {
                 UI.Show(msg);
diff --git a/v2rayN/v2rayN/Forms/AddServerForm.cs b/v2rayN/v2rayN/Forms/AddServerForm.cs
index 0fcf647b..6d09db03 100644
--- a/v2rayN/v2rayN/Forms/AddServerForm.cs
+++ b/v2rayN/v2rayN/Forms/AddServerForm.cs
@@ -258,8 +258,7 @@ namespace v2rayN.Forms
         {
             ClearServer();
 
-            string msg;
-            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out msg);
+            VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(Utils.GetClipboardData(), out string msg);
             if (vmessItem == null)
             {
                 UI.Show(msg);
diff --git a/v2rayN/v2rayN/Forms/OptionSettingForm.cs b/v2rayN/v2rayN/Forms/OptionSettingForm.cs
index 8a0000ff..c1152594 100644
--- a/v2rayN/v2rayN/Forms/OptionSettingForm.cs
+++ b/v2rayN/v2rayN/Forms/OptionSettingForm.cs
@@ -77,8 +77,7 @@ namespace v2rayN.Forms
         {
             //路由
             cmbdomainStrategy.Text = config.domainStrategy;
-            int routingMode = 0;
-            int.TryParse(config.routingMode, out routingMode);
+            int.TryParse(config.routingMode, out int routingMode);
             cmbroutingMode.SelectedIndex = routingMode;
 
             txtUseragent.Text = Utils.List2String(config.useragent, true);
diff --git a/v2rayN/v2rayN/Handler/ConfigHandler.cs b/v2rayN/v2rayN/Handler/ConfigHandler.cs
index acb42953..741976bb 100644
--- a/v2rayN/v2rayN/Handler/ConfigHandler.cs
+++ b/v2rayN/v2rayN/Handler/ConfigHandler.cs
@@ -753,7 +753,6 @@ namespace v2rayN.Handler
             string[] arrData = clipboardData.Split(Environment.NewLine.ToCharArray());
             foreach (string str in arrData)
             {
-                string msg;
                 //maybe sub
                 if (str.StartsWith(Global.httpsProtocol) || str.StartsWith(Global.httpProtocol))
                 {
@@ -763,7 +762,7 @@ namespace v2rayN.Handler
                     }
                     continue;
                 }
-                VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(str, out msg);
+                VmessItem vmessItem = V2rayConfigHandler.ImportFromClipboardConfig(str, out string msg);
                 if (vmessItem == null)
                 {
                     continue;
diff --git a/v2rayN/v2rayN/Handler/MainFormHandler.cs b/v2rayN/v2rayN/Handler/MainFormHandler.cs
index c105359a..6e9243d6 100644
--- a/v2rayN/v2rayN/Handler/MainFormHandler.cs
+++ b/v2rayN/v2rayN/Handler/MainFormHandler.cs
@@ -102,8 +102,7 @@ namespace v2rayN.Handler
             }
             Config configCopy = Utils.DeepCopy(config);
             configCopy.index = index;
-            string msg;
-            if (V2rayConfigHandler.Export2ClientConfig(configCopy, fileName, out msg) != 0)
+            if (V2rayConfigHandler.Export2ClientConfig(configCopy, fileName, out string msg) != 0)
             {
                 UI.Show(msg);
             }
@@ -143,8 +142,7 @@ namespace v2rayN.Handler
             }
             Config configCopy = Utils.DeepCopy(config);
             configCopy.index = index;
-            string msg;
-            if (V2rayConfigHandler.Export2ServerConfig(configCopy, fileName, out msg) != 0)
+            if (V2rayConfigHandler.Export2ServerConfig(configCopy, fileName, out string msg) != 0)
             {
                 UI.Show(msg);
             }
diff --git a/v2rayN/v2rayN/Handler/SpeedtestHandler.cs b/v2rayN/v2rayN/Handler/SpeedtestHandler.cs
index c64d6dab..b8e43bc9 100644
--- a/v2rayN/v2rayN/Handler/SpeedtestHandler.cs
+++ b/v2rayN/v2rayN/Handler/SpeedtestHandler.cs
@@ -221,8 +221,7 @@ namespace v2rayN.Handler
 
             try
             {
-                IPAddress ipAddress;
-                if (!System.Net.IPAddress.TryParse(url, out ipAddress))
+                if (!System.Net.IPAddress.TryParse(url, out IPAddress ipAddress))
                 {
                     IPHostEntry ipHostInfo = System.Net.Dns.GetHostEntry(url);
                     ipAddress = ipHostInfo.AddressList[0];
diff --git a/v2rayN/v2rayN/Handler/StatisticsHandler.cs b/v2rayN/v2rayN/Handler/StatisticsHandler.cs
index 23a41f60..c4117ba4 100644
--- a/v2rayN/v2rayN/Handler/StatisticsHandler.cs
+++ b/v2rayN/v2rayN/Handler/StatisticsHandler.cs
@@ -120,11 +120,9 @@ namespace v2rayN.Handler
                         {
                             string itemId = config_.getItemId();
                             ServerStatItem serverStatItem = GetServerStatItem(itemId);
-                            ulong up = 0,
-                                 down = 0;
 
                             //TODO: parse output
-                            ParseOutput(res.Stat, out up, out down);
+                            ParseOutput(res.Stat, out ulong up, out ulong down);
 
                             serverStatItem.todayUp += up;
                             serverStatItem.todayDown += down;
diff --git a/v2rayN/v2rayN/Tool/Utils.cs b/v2rayN/v2rayN/Tool/Utils.cs
index c4fc5acc..bbca80c8 100644
--- a/v2rayN/v2rayN/Tool/Utils.cs
+++ b/v2rayN/v2rayN/Tool/Utils.cs
@@ -314,9 +314,7 @@ namespace v2rayN
 
         public static string HumanFy(ulong amount)
         {
-            double result;
-            string unit;
-            ToHumanReadable(amount, out result, out unit);
+            ToHumanReadable(amount, out double result, out string unit);
             return $"{string.Format("{0:f1}", result)} {unit}";
         }