diff --git a/src/Avalonia.Controls/Window.cs b/src/Avalonia.Controls/Window.cs
index 4b6df20363..07e3d78650 100644
--- a/src/Avalonia.Controls/Window.cs
+++ b/src/Avalonia.Controls/Window.cs
@@ -376,7 +376,7 @@ namespace Avalonia.Controls
 
         private void CloseInternal ()
         {
-            foreach(var child in _children)
+            foreach(var child in _children.ToList())
             {
                 // if we HandleClosing() before then there will be no children.
                 child.CloseInternal();