diff --git a/WinPowerHelper.Wpf/App.xaml b/WinPowerHelper.Wpf/App.xaml
index 7981f7e..084f8e9 100644
--- a/WinPowerHelper.Wpf/App.xaml
+++ b/WinPowerHelper.Wpf/App.xaml
@@ -2,8 +2,8 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:viewmodels="clr-namespace:WinPowerHelper.Wpf.ViewModels"
-             StartupUri="MainWindow.xaml"
-             xmlns:system="clr-namespace:System;assembly=System.Runtime">
+             xmlns:system="clr-namespace:System;assembly=System.Runtime"
+             StartupUri="MainWindow.xaml">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>
diff --git a/WinPowerHelper.Wpf/App.xaml.cs b/WinPowerHelper.Wpf/App.xaml.cs
index 6d383fe..99e5925 100644
--- a/WinPowerHelper.Wpf/App.xaml.cs
+++ b/WinPowerHelper.Wpf/App.xaml.cs
@@ -1,11 +1,32 @@
 namespace WinPowerHelper
 {
+    using System;
+    using System.Threading;
     using System.Windows;
+    using WinPowerHelper.Wpf.Interaction;
 
     /// <summary>
     /// Interaction logic for App.xaml
     /// </summary>
     public partial class App : Application
     {
+        public App()
+        {
+            Startup += (e, args) =>
+            {
+                _mutex = new Mutex(true, "WinPowerHelper", out bool isNew);
+                if (!isNew)
+                {
+                    NativeMethods.PostMessage(
+                        (IntPtr)NativeMethods.HWND_BROADCAST,
+                        NativeMethods.WM_SHOWME,
+                        IntPtr.Zero,
+                        IntPtr.Zero);
+                    Environment.Exit(0);
+                }
+            };
+        }
+
+        private Mutex _mutex;
     }
 }
diff --git a/WinPowerHelper.Wpf/Interaction/NativeMethods.cs b/WinPowerHelper.Wpf/Interaction/NativeMethods.cs
new file mode 100644
index 0000000..798c4bc
--- /dev/null
+++ b/WinPowerHelper.Wpf/Interaction/NativeMethods.cs
@@ -0,0 +1,15 @@
+namespace WinPowerHelper.Wpf.Interaction
+{
+    using System;
+    using System.Runtime.InteropServices;
+
+    internal class NativeMethods
+    {
+        public const int HWND_BROADCAST = 0xffff;
+        public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");
+        [DllImport("user32")]
+        public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
+        [DllImport("user32", CharSet = CharSet.Unicode)]
+        public static extern int RegisterWindowMessage(string message);
+    }
+}
diff --git a/WinPowerHelper.Wpf/MainWindow.xaml.cs b/WinPowerHelper.Wpf/MainWindow.xaml.cs
index 817bcd9..961e550 100644
--- a/WinPowerHelper.Wpf/MainWindow.xaml.cs
+++ b/WinPowerHelper.Wpf/MainWindow.xaml.cs
@@ -1,6 +1,9 @@
 namespace WinPowerHelper
 {
+    using System;
     using System.Windows;
+    using System.Windows.Interop;
+    using WinPowerHelper.Wpf.Interaction;
 
     /// <summary>
     /// Interaction logic for MainWindow.xaml
@@ -11,5 +14,19 @@ public MainWindow()
         {
             InitializeComponent();
         }
+
+        protected override void OnSourceInitialized(EventArgs e)
+        {
+            base.OnSourceInitialized(e);
+            var source = PresentationSource.FromVisual(this) as HwndSource;
+            source.AddHook(WndProc);
+        }
+
+        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
+        {
+            if (msg == NativeMethods.WM_SHOWME)
+                Activate();
+            return IntPtr.Zero;
+        }
     }
 }