diff --git a/src/Avalonia.Base/Layout/LayoutManager.cs b/src/Avalonia.Base/Layout/LayoutManager.cs
index 91358adc05..b9ca6bfbd7 100644
--- a/src/Avalonia.Base/Layout/LayoutManager.cs
+++ b/src/Avalonia.Base/Layout/LayoutManager.cs
@@ -414,7 +414,7 @@ namespace Avalonia.Layout
             }
         }
 
-        private struct EffectiveViewportChangedListener
+        private class EffectiveViewportChangedListener
         {
             public EffectiveViewportChangedListener(ILayoutable listener, Rect viewport)
             {