diff --git a/src/Avalonia.Controls.TreeDataGrid/Selection/TreeSelectedItems.cs b/src/Avalonia.Controls.TreeDataGrid/Selection/TreeSelectedItems.cs
index 19494388..7ec49a79 100644
--- a/src/Avalonia.Controls.TreeDataGrid/Selection/TreeSelectedItems.cs
+++ b/src/Avalonia.Controls.TreeDataGrid/Selection/TreeSelectedItems.cs
@@ -52,15 +52,18 @@ public T? this[int index]
 
         private IEnumerable<T?> EnumerateNode(TreeSelectionNode<T> node)
         {
-            foreach (var range in node.Ranges)
+            if (node.ItemsView is not null)
             {
-                for (var i = range.Begin; i <= range.End; ++i)
+                foreach (var range in node.Ranges)
                 {
-                    yield return node.ItemsView![i];
+                    for (var i = range.Begin; i <= range.End; ++i)
+                    {
+                        yield return node.ItemsView[i];
+                    }
                 }
             }
 
-            if (node.Children is object)
+            if (node.Children is not null)
             {
                 foreach (var child in node.Children)
                 {
@@ -110,4 +113,4 @@ public TreeSelectedItems(TreeSelectionModelBase<T> root) : base(root) { }
                 yield return i;
         }
     }
-}
\ No newline at end of file
+}