diff --git a/shadowsocks-csharp/Controller/Logging.cs b/shadowsocks-csharp/Controller/Logging.cs
index 5a017a3b..39452b64 100755
--- a/shadowsocks-csharp/Controller/Logging.cs
+++ b/shadowsocks-csharp/Controller/Logging.cs
@@ -12,8 +12,8 @@ namespace Shadowsocks.Controller
     {
         public static string LogFilePath;
 
-        private static FileStream fs;
-        private static StreamWriterWithTimestamp sw;
+        private static FileStream _fs;
+        private static StreamWriterWithTimestamp _sw;
 
         public static bool OpenLogFile()
         {
@@ -21,11 +21,11 @@ namespace Shadowsocks.Controller
             {
                 LogFilePath = Utils.GetTempPath("shadowsocks.log");
 
-                fs = new FileStream(LogFilePath, FileMode.Append);
-                sw = new StreamWriterWithTimestamp(fs);
-                sw.AutoFlush = true;
-                Console.SetOut(sw);
-                Console.SetError(sw);
+                _fs = new FileStream(LogFilePath, FileMode.Append);
+                _sw = new StreamWriterWithTimestamp(_fs);
+                _sw.AutoFlush = true;
+                Console.SetOut(_sw);
+                Console.SetError(_sw);
 
                 return true;
             }
@@ -54,11 +54,11 @@ namespace Shadowsocks.Controller
             WriteToLogFile(o);
         }
 
-        public static void clear() {
-            sw.Close();
-            sw.Dispose();
-            fs.Close();
-            fs.Dispose();
+        public static void Clear() {
+            _sw.Close();
+            _sw.Dispose();
+            _fs.Close();
+            _fs.Dispose();
             File.Delete(LogFilePath);
             OpenLogFile();
         }
diff --git a/shadowsocks-csharp/Controller/Service/PACServer.cs b/shadowsocks-csharp/Controller/Service/PACServer.cs
index 3fb0461a..a04a5e0e 100644
--- a/shadowsocks-csharp/Controller/Service/PACServer.cs
+++ b/shadowsocks-csharp/Controller/Service/PACServer.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections;
+using System.Globalization;
 using System.IO;
 using System.Net;
 using System.Net.Sockets;
@@ -69,7 +70,7 @@ namespace Shadowsocks.Controller
                     }
                     else if (kv.Length == 1)
                     {
-                        if (line.IndexOf("pac") >= 0)
+                        if (line.IndexOf("pac", StringComparison.Ordinal) >= 0)
                         {
                             pathMatch = true;
                         }
@@ -207,7 +208,7 @@ Connection: Close
         private void PACFileWatcher_Changed(object sender, FileSystemEventArgs e)
         {
             string path = e.FullPath.ToString();
-            string currentLastWriteTime = File.GetLastWriteTime(e.FullPath).ToString();
+            string currentLastWriteTime = File.GetLastWriteTime(e.FullPath).ToString(CultureInfo.InvariantCulture);
 
             // if there is no path info stored yet or stored path has different time of write then the one now is inspected
             if (!fileChangedTime.ContainsKey(path) || fileChangedTime[path].ToString() != currentLastWriteTime)
@@ -226,7 +227,7 @@ Connection: Close
         private void UserRuleFileWatcher_Changed(object sender, FileSystemEventArgs e)
         {
             string path = e.FullPath.ToString();
-            string currentLastWriteTime = File.GetLastWriteTime(e.FullPath).ToString();
+            string currentLastWriteTime = File.GetLastWriteTime(e.FullPath).ToString(CultureInfo.InvariantCulture);
 
             // if there is no path info stored yet or stored path has different time of write then the one now is inspected
             if (!fileChangedTime.ContainsKey(path) || fileChangedTime[path].ToString() != currentLastWriteTime)
diff --git a/shadowsocks-csharp/Controller/Service/TCPRelay.cs b/shadowsocks-csharp/Controller/Service/TCPRelay.cs
index 7a80fefb..1c02ca25 100644
--- a/shadowsocks-csharp/Controller/Service/TCPRelay.cs
+++ b/shadowsocks-csharp/Controller/Service/TCPRelay.cs
@@ -176,7 +176,13 @@ namespace Shadowsocks.Controller
             Server server = controller.GetAServer(IStrategyCallerType.TCP, (IPEndPoint)connection.RemoteEndPoint);
             if (server == null || server.server == "")
                 throw new ArgumentException("No server configured");
-            encryptor = EncryptorFactory.GetEncryptor(server.method, server.password, server.auth, false);
+            lock (_encryptionLock)
+            {
+                lock (_decryptionLock)
+                {
+                    encryptor = EncryptorFactory.GetEncryptor(server.method, server.password, server.auth, false);
+                }
+            }
             this.server = server;
         }
 
diff --git a/shadowsocks-csharp/Controller/Service/UpdateChecker.cs b/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
index 5fd6f396..4db01a0f 100644
--- a/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
+++ b/shadowsocks-csharp/Controller/Service/UpdateChecker.cs
@@ -198,7 +198,7 @@ namespace Shadowsocks.Controller
                 name = (string)asset["name"];
                 browser_download_url = (string)asset["browser_download_url"];
                 version = ParseVersionFromURL(browser_download_url);
-                prerelease = browser_download_url.IndexOf("prerelease") >= 0;
+                prerelease = browser_download_url.IndexOf("prerelease", StringComparison.Ordinal) >= 0;
             }
 
             private static string ParseVersionFromURL(string url)
diff --git a/shadowsocks-csharp/View/LogForm.cs b/shadowsocks-csharp/View/LogForm.cs
index 7aab4e8e..c84d6dcc 100644
--- a/shadowsocks-csharp/View/LogForm.cs
+++ b/shadowsocks-csharp/View/LogForm.cs
@@ -247,7 +247,7 @@ namespace Shadowsocks.View
         #region Clean up the content in LogMessageTextBox.
         private void DoCleanLogs()
         {
-            Logging.clear();
+            Logging.Clear();
             lastOffset = 0;
             LogMessageTextBox.Clear();
         }