diff --git a/src/App.preference.cs b/src/App.preference.cs
index f00d297c..d51fe99a 100644
--- a/src/App.preference.cs
+++ b/src/App.preference.cs
@@ -106,6 +106,10 @@ namespace SourceGit {
         /// </summary>
         public bool CheckUpdate { get; set; } = true;
         /// <summary>
+        ///     Last UNIX timestamp to check for update.
+        /// </summary>
+        public int LastCheckUpdate { get; set; } = 0;
+        /// <summary>
         ///     Settings for executables.
         /// </summary>
         public ToolSetting Tools { get; set; } = new ToolSetting();
diff --git a/src/App.xaml.cs b/src/App.xaml.cs
index d8fb11a1..c2c2f757 100644
--- a/src/App.xaml.cs
+++ b/src/App.xaml.cs
@@ -2,6 +2,11 @@ using Microsoft.Win32;
 using Newtonsoft.Json;
 using System;
 using System.IO;
+using System.Net;
+using System.Reflection;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
 using System.Windows;
 
 namespace SourceGit {
@@ -105,8 +110,15 @@ namespace SourceGit {
             }
 
             // Show main window
-            Current.MainWindow = new UI.Launcher();
-            Current.MainWindow.Show();
+            MainWindow = new UI.Launcher();
+            MainWindow.Show();
+
+            // Check for update.
+            if (Setting.CheckUpdate && Setting.LastCheckUpdate != DateTime.Now.DayOfYear) {
+                Setting.LastCheckUpdate = DateTime.Now.DayOfYear;
+                SaveSetting();
+                Task.Run(CheckUpdate);
+            }
         }
 
         /// <summary>
@@ -116,7 +128,7 @@ namespace SourceGit {
         /// <param name="e"></param>
         private void OnAppDeactivated(object sender, EventArgs e) {
             GC.Collect();
-            SaveSetting();            
+            SaveSetting();
         }
 
         /// <summary>
@@ -142,5 +154,32 @@ namespace SourceGit {
 
             return true;
         }
+
+        /// <summary>
+        ///     Check for update.
+        /// </summary>
+        private void CheckUpdate() {
+            try {
+                var web = new WebClient() { Encoding = Encoding.UTF8 };
+                var raw = web.DownloadString("https://gitee.com/api/v5/repos/sourcegit/SourceGit/releases/latest");
+                var ver = JsonConvert.DeserializeObject<Git.Version>(raw);
+                var cur = Assembly.GetExecutingAssembly().GetName().Version;
+
+                var matches = Regex.Match(ver.TagName, @"^v(\d+)\.(\d+).*");
+                if (!matches.Success) return;
+
+                var major = int.Parse(matches.Groups[1].Value);
+                var minor = int.Parse(matches.Groups[2].Value);
+                if (major > cur.Major || (major == cur.Major && minor > cur.Minor)) {
+                    Dispatcher.Invoke(() => {
+                        var dialog = new UI.UpdateAvailable(ver);
+                        dialog.Owner = MainWindow;
+                        dialog.ShowDialog();
+                    });
+                }
+            } catch {
+                // IGNORE
+            }
+        }
     }
 }
diff --git a/src/UI/Launcher.xaml.cs b/src/UI/Launcher.xaml.cs
index 2f30b00b..1cc6d1d8 100644
--- a/src/UI/Launcher.xaml.cs
+++ b/src/UI/Launcher.xaml.cs
@@ -1,16 +1,9 @@
-using Newtonsoft.Json;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
-using System.Net;
-using System.Reflection;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
-using System.Windows.Shapes;
 
 namespace SourceGit.UI {
 
@@ -105,7 +98,6 @@ namespace SourceGit.UI {
         public Launcher() {
             InitializeComponent();
             NewTab(null, null);
-            if (App.Setting.CheckUpdate) Task.Run(CheckUpdate);
         }
 
         /// <summary>
@@ -135,33 +127,6 @@ namespace SourceGit.UI {
             }
         }
 
-        /// <summary>
-        ///     Checking for update.
-        /// </summary>
-        public void CheckUpdate() {
-            try {
-                var web = new WebClient() { Encoding = Encoding.UTF8 };
-                var raw = web.DownloadString("https://gitee.com/api/v5/repos/sourcegit/SourceGit/releases/latest");
-                var ver = JsonConvert.DeserializeObject<Git.Version>(raw);
-                var cur = Assembly.GetExecutingAssembly().GetName().Version;
-
-                var matches = Regex.Match(ver.TagName, @"^v(\d+)\.(\d+).*");
-                if (!matches.Success) return;
-
-                var major = int.Parse(matches.Groups[1].Value);
-                var minor = int.Parse(matches.Groups[2].Value);
-                if (major > cur.Major || (major == cur.Major && minor > cur.Minor)) {
-                    Dispatcher.Invoke(() => {
-                        var dialog = new UpdateAvailable(ver);
-                        dialog.Owner = this;
-                        dialog.ShowDialog();
-                    });
-                }
-            } catch {
-                // IGNORE
-            }
-        }
-
         #region LAYOUT_CONTENT
         /// <summary>
         ///     Add new tab.