diff --git a/IAppWindow.cs b/IAppWindow.cs
index b67e5ed..935988f 100644
--- a/IAppWindow.cs
+++ b/IAppWindow.cs
@@ -12,9 +12,9 @@ public interface IAppWindow
         Rect Bounds { get; }
         Task<Rect> GetBounds();
         Task<Rect> GetClientBounds();
-        string Title { get; }
-        Task<Exception> Activate();
-        Task<Exception> BringToFront();
+        string? Title { get; }
+        Task<Exception?> Activate();
+        Task<Exception?> BringToFront();
         bool IsMinimized { get; }
         bool IsResizable { get; }
         bool IsVisible { get; }