diff --git a/SudokuSolver/App.xaml.cs b/SudokuSolver/App.xaml.cs
index 57a3041..b919046 100644
--- a/SudokuSolver/App.xaml.cs
+++ b/SudokuSolver/App.xaml.cs
@@ -208,7 +208,7 @@ internal void RegisterWindow(MainWindow window)
         currentWindow = window;
     }
 
-    internal bool UnRegisterWindow(MainWindow window)
+    internal void UnRegisterWindow(MainWindow window)
     {
         appClosing = windowList.Count == 1;
 
@@ -221,8 +221,6 @@ internal bool UnRegisterWindow(MainWindow window)
         {
             currentWindow = windowList.LastOrDefault();
         }
-
-        return appClosing;
     }
 
     public int WindowCount => windowList.Count;
diff --git a/SudokuSolver/Views/MainWindow.xaml.cs b/SudokuSolver/Views/MainWindow.xaml.cs
index 772a6df..0ca2c00 100644
--- a/SudokuSolver/Views/MainWindow.xaml.cs
+++ b/SudokuSolver/Views/MainWindow.xaml.cs
@@ -208,9 +208,9 @@ private async void Tabs_TabItemsChangedAsync(TabView sender, IVectorChangedEvent
 
             AppWindow.Hide();
 
-            bool isLastWindow = App.Instance.UnRegisterWindow(this);
+            App.Instance.UnRegisterWindow(this);
 
-            if (isLastWindow)
+            if (App.Instance.WindowCount == 0)
             {
                 await Settings.Data.SaveAsync();
             }