diff --git a/Manager/MainWindow.xaml.cs b/Manager/MainWindow.xaml.cs
index 841347e..0386e08 100644
--- a/Manager/MainWindow.xaml.cs
+++ b/Manager/MainWindow.xaml.cs
@@ -39,7 +39,10 @@ namespace BetterSeewo.Manager
         private void ShowPage(StackPanel page)
         {
             foreach (var p in new[] { PageInstall, PageInk, PageConvert, PageTouch, PageActivate })
-                p.Visibility = p == page ? Visibility.Visible : Visibility.Collapsed;
+            {
+                if (p != null)
+                    p.Visibility = p == page ? Visibility.Visible : Visibility.Collapsed;
+            }
         }
 
         private void Minimize_Click(object s, RoutedEventArgs e) => WindowState = WindowState.Minimized;