diff --git a/src/AppContext.cs b/src/AppContext.cs
index 5254c09..9e65c75 100644
--- a/src/AppContext.cs
+++ b/src/AppContext.cs
@@ -3,7 +3,6 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 using System;
-using System.Linq;
 using System.Reflection;
 using System.Windows.Forms;
 
@@ -23,8 +22,8 @@ public AppContext(string[] args) : base(new HiddenForm())
             Localization.Initialize();
             LoggingHandler.RotateDebugLog();
 
-            ThemeManager.importPaths = args.Where(System.IO.File.Exists).ToList();
-            HandleMultiInstance(args);
+            CheckSingleInstance(args);
+            ipcManager.ProcessArgs(args);
 
             InitializeTrayIcon();
             LocationManager.Initialize();
@@ -36,13 +35,13 @@ public AppContext(string[] args) : base(new HiddenForm())
             UpdateChecker.Initialize();
         }
 
-        private void HandleMultiInstance(string[] args)
+        private void CheckSingleInstance(string[] args)
         {
             ipcManager = new IpcManager();
 
             if (ipcManager.isFirstInstance)
             {
-                ipcManager.ListenForArgs(OnArgumentsReceived);
+                ipcManager.ListenForArgs(this);
             }
             else
             {
@@ -92,48 +91,6 @@ public static void ToggleTrayIcon()
             notifyIcon.Visible = !isHidden;
         }
 
-        private void OnArgumentsReceived(string[] args)
-        {
-            if (JsonConfig.settings.hideTrayIcon)
-            {
-                MainForm.BeginInvoke(ToggleTrayIcon);
-            }
-
-            foreach (string arg in args)
-            {
-                if (arg.StartsWith('/'))
-                {
-                    switch (arg.ToLower())
-                    {
-                        case "/refresh":
-                            scheduler.RunAndUpdateLocation(true);
-                            break;
-                        case "/theme:auto":
-                            MainForm.BeginInvoke(SolarScheduler.SetAppearanceMode, AppearanceMode.Automatic);
-                            break;
-                        case "/theme:light":
-                            MainForm.BeginInvoke(SolarScheduler.SetAppearanceMode, AppearanceMode.Light); 
-                            break;
-                        case "/theme:dark":
-                            MainForm.BeginInvoke(SolarScheduler.SetAppearanceMode, AppearanceMode.Dark);
-                            break;
-                        default:
-                            Console.WriteLine("Unrecognized command line option: " + arg);
-                            break;
-                    }
-                }
-                else
-                {
-                    ThemeManager.importPaths.Add(arg);
-                }
-            }
-
-            if (ThemeManager.importPaths.Count > 0 && !ThemeManager.importMode)
-            {
-                MainForm.BeginInvoke(ThemeManager.SelectTheme);
-            }
-        }
-
         private void OnNotifyIconMouseUp(object sender, MouseEventArgs e)
         {
             // Show context menu when taskbar icon is left clicked
diff --git a/src/IpcManager.cs b/src/IpcManager.cs
index 3b1a9b5..1faffaf 100644
--- a/src/IpcManager.cs
+++ b/src/IpcManager.cs
@@ -7,6 +7,7 @@
 using System.IO.Pipes;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Windows.Forms;
 
 namespace WinDynamicDesktop
 {
@@ -30,7 +31,7 @@ public void Dispose()
             namedPipeServer?.Dispose();
         }
 
-        public void ListenForArgs(Action<string[]> listener)
+        public void ListenForArgs(ApplicationContext app)
         {
             Task.Factory.StartNew(() =>
             {
@@ -44,7 +45,8 @@ public void ListenForArgs(Action<string[]> listener)
                         namedPipeServer.WaitForConnection();
                     }
 
-                    listener(reader.ReadToEnd().Split(Environment.NewLine, StringSplitOptions.RemoveEmptyEntries));
+                    ProcessArgs(app, reader.ReadToEnd().Split(Environment.NewLine,
+                        StringSplitOptions.RemoveEmptyEntries));
                     namedPipeServer.Disconnect();
                 }
             }, TaskCreationOptions.LongRunning);
@@ -59,5 +61,115 @@ public void SendArgsToFirstInstance(string[] args)
             writer.Write(string.Join(Environment.NewLine, args));
             writer.Flush();
         }
+
+        public void ProcessArgs(string[] initialArgs)
+        {
+            foreach (string arg in initialArgs)
+            {
+                if (arg.ToLower().StartsWith("/theme") && arg.IndexOf('=') != -1)
+                {
+                    ProcessThemeArg(arg.ToLower());
+                }
+                else if (arg.StartsWith('/'))
+                {
+                    switch (arg.ToLower())
+                    {
+                        case "/refresh":
+                            break;
+                        case "/theme:auto":
+                        case "/theme:light":
+                        case "/theme:dark":
+                            AppearanceMode mode = (AppearanceMode)Enum.Parse(typeof(AppearanceMode),
+                                arg.Substring(7), true);
+                            JsonConfig.settings.appearanceMode = (int)mode;
+                            break;
+                        default:
+                            Console.WriteLine("Unrecognized command line option: " + arg);
+                            break;
+                    }
+                }
+                else if (File.Exists(arg))
+                {
+                    ThemeManager.importPaths.Add(arg);
+                }
+            }
+        }
+
+        private void ProcessArgs(ApplicationContext app, string[] args)
+        {
+            if (JsonConfig.settings.hideTrayIcon)
+            {
+                app.MainForm.BeginInvoke(AppContext.ToggleTrayIcon);
+            }
+
+            foreach (string arg in args)
+            {
+                if (arg.ToLower().StartsWith("/theme") && arg.IndexOf('=') != -1)
+                {
+                    string themeId = ProcessThemeArg(arg.ToLower());
+                    if (themeId != null)
+                    {
+                        ThemeShuffler.AddThemeToHistory(themeId);
+                        AppContext.scheduler.Run(true);
+                    }
+                }
+                else if (arg.StartsWith('/'))
+                {
+                    switch (arg.ToLower())
+                    {
+                        case "/refresh":
+                            AppContext.scheduler.RunAndUpdateLocation(true);
+                            break;
+                        case "/theme:auto":
+                        case "/theme:light":
+                        case "/theme:dark":
+                            AppearanceMode mode = (AppearanceMode)Enum.Parse(typeof(AppearanceMode),
+                                arg.Substring(7), true);
+                            app.MainForm.BeginInvoke(SolarScheduler.SetAppearanceMode, mode);
+                            break;
+                        default:
+                            Console.WriteLine("Unrecognized command line option: " + arg);
+                            break;
+                    }
+                }
+                else if (File.Exists(arg))
+                {
+                    ThemeManager.importPaths.Add(arg);
+                }
+            }
+
+            if (ThemeManager.importPaths.Count > 0 && !ThemeManager.importMode)
+            {
+                app.MainForm.BeginInvoke(ThemeManager.SelectTheme);
+            }
+        }
+
+        private string ProcessThemeArg(string arg)
+        {
+            string themeId = arg.Substring(arg.IndexOf('=') + 1);
+            if (ThemeManager.themeSettings.Find((theme) => theme.themeId == themeId) == null)
+            {
+                Console.WriteLine("Failed to set theme - unknown theme ID: " + themeId);
+                return null;
+            }
+
+            if (arg.StartsWith("/theme="))
+            {
+                JsonConfig.settings.activeThemes[0] = themeId;
+            }
+            else if (arg.StartsWith("/theme:L="))
+            {
+                JsonConfig.settings.lockScreenTheme = themeId;
+                JsonConfig.settings.lockScreenDisplayIndex = -1;
+            }
+            else
+            {
+                int displayNumber = int.Parse(arg[7].ToString());
+                JsonConfig.settings.activeThemes[displayNumber] = themeId;
+                JsonConfig.settings.activeThemes[0] = null;
+            }
+
+            return themeId;
+        }
     }
 }
diff --git a/src/SolarScheduler.cs b/src/SolarScheduler.cs
index 7ef44b0..51a9a82 100644
--- a/src/SolarScheduler.cs
+++ b/src/SolarScheduler.cs
@@ -8,7 +8,7 @@
 
 namespace WinDynamicDesktop
 {
-    public enum AppearanceMode { Automatic, Light, Dark }
+    public enum AppearanceMode { Automatic, Auto = Automatic, Light, Dark }
 
     public enum DaySegment { Sunrise, Day, Sunset, Night, AlwaysDay, AlwaysNight }
 
diff --git a/src/ThemeManager.cs b/src/ThemeManager.cs
index 5fbe29d..965800d 100644
--- a/src/ThemeManager.cs
+++ b/src/ThemeManager.cs
@@ -19,7 +19,7 @@ class ThemeManager
 
         public static bool downloadMode = false;
         public static bool importMode = false;
-        public static List<string> importPaths;
+        public static List<string> importPaths = new List<string>();
         public static List<ThemeConfig> importedThemes = new List<ThemeConfig>();
 
         public static string[] defaultThemes;