diff --git a/Gu.Wpf.NumericInput/Touch/TextBox.cs b/Gu.Wpf.NumericInput/Touch/TextBox.cs
index 15652e7..30fe05b 100644
--- a/Gu.Wpf.NumericInput/Touch/TextBox.cs
+++ b/Gu.Wpf.NumericInput/Touch/TextBox.cs
@@ -29,11 +29,14 @@ static TextBox()
                 typeof(System.Windows.Controls.TextBox),
                 UIElement.LostFocusEvent,
                 new RoutedEventHandler(OnLostFocus));
-            var mainWindow = Application.Current?.MainWindow;
-            if (mainWindow != null)
+            Application.Current.Dispatcher.Invoke(() =>
             {
-                mainWindow.Closed += OnClosed;
-            }
+                var mainWindow = Application.Current?.MainWindow;
+                if (mainWindow != null)
+                {
+                    mainWindow.Closed += OnClosed;
+                }
+            });
         }
 
         /// <summary>Helper for setting <see cref="ShowTouchKeyboardOnTouchEnterProperty"/> on <paramref name="element"/>.</summary>