diff --git a/shadowsocks-csharp/Controller/System/AutoStartup.cs b/shadowsocks-csharp/Controller/System/AutoStartup.cs
index 9f3e5ff2..e2031788 100644
--- a/shadowsocks-csharp/Controller/System/AutoStartup.cs
+++ b/shadowsocks-csharp/Controller/System/AutoStartup.cs
@@ -115,6 +115,7 @@ namespace Shadowsocks.Controller
         [DllImport("kernel32.dll", SetLastError = true)]
         static extern int UnregisterApplicationRestart();
 
+        [Flags]
         enum ApplicationRestartFlags
         {
             RESTART_NO_CRASH = 1,
@@ -137,7 +138,7 @@ namespace Shadowsocks.Controller
                 string cmdline = string.Join(" ", args);
                 // first parameter is process command line parameter
                 // needn't include the name of the executable in the command line
-                RegisterApplicationRestart(cmdline, (int)ApplicationRestartFlags.RESTART_NO_CRASH | (int)ApplicationRestartFlags.RESTART_NO_HANG);
+                RegisterApplicationRestart(cmdline, (int)(ApplicationRestartFlags.RESTART_NO_CRASH | ApplicationRestartFlags.RESTART_NO_HANG));
                 Logging.Debug("Register restart after system reboot, command line:" + cmdline);
             }
             // requested unregister, which has no side effect