diff --git a/src/AdvancedCalculator/App.axaml.cs b/src/AdvancedCalculator/App.axaml.cs
index 32716eb..291f710 100644
--- a/src/AdvancedCalculator/App.axaml.cs
+++ b/src/AdvancedCalculator/App.axaml.cs
@@ -5,6 +5,7 @@ using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Data.Core.Plugins;
 using Avalonia.Markup.Xaml;
+using Avalonia.Markup.Xaml.Styling;
 using Avalonia.Styling;
 using System;