diff --git a/src/Semi.Avalonia.TreeDataGrid/Shared.axaml b/src/Semi.Avalonia.TreeDataGrid/Shared.axaml
index 17b1497..e421078 100644
--- a/src/Semi.Avalonia.TreeDataGrid/Shared.axaml
+++ b/src/Semi.Avalonia.TreeDataGrid/Shared.axaml
@@ -2,6 +2,7 @@
     <StaticResource x:Key="TreeDataGridSortIconAscendingPath" ResourceKey="SemiIconSmallTriangleTop" />
     <StaticResource x:Key="TreeDataGridSortIconDescendingPath" ResourceKey="SemiIconSmallTriangleDown" />
     <StaticResource x:Key="TreeDataGridItemCollapsedChevronPathData" ResourceKey="SemiIconTreeTriangleRight" />
+    <StaticResource x:Key="TreeDataGridItemCollapsedChevronWidth" ResourceKey="SemiWidthIconMedium" />
     <StaticResource x:Key="TreeDataGridColumnHeaderCornerRadius" ResourceKey="SemiBorderRadiusSmall" />
     <StaticResource x:Key="TreeDataGridColumnHeaderMinHeight" ResourceKey="SemiHeightControlDefault" />
     <StaticResource x:Key="TreeDataGridRowCornerRadius" ResourceKey="SemiBorderRadiusSmall" />
diff --git a/src/Semi.Avalonia.TreeDataGrid/TreeDataGrid.axaml b/src/Semi.Avalonia.TreeDataGrid/TreeDataGrid.axaml
index 8768a53..845ed27 100644
--- a/src/Semi.Avalonia.TreeDataGrid/TreeDataGrid.axaml
+++ b/src/Semi.Avalonia.TreeDataGrid/TreeDataGrid.axaml
@@ -220,6 +220,7 @@
                     <DockPanel>
                         <Border
                             DockPanel.Dock="Left"
+                            Width="{DynamicResource TreeDataGridItemCollapsedChevronWidth}"
                             Margin="4,0">
                             <ToggleButton
                                 Focusable="False"