diff --git a/lcl/comctrls.pp b/lcl/comctrls.pp
index 42a8a2e93e..b946c4ba32 100644
--- a/lcl/comctrls.pp
+++ b/lcl/comctrls.pp
@@ -3199,6 +3199,7 @@ const
                             tvoKeepCollapsedNodes, tvoAutoItemHeight, tvoThemedDraw];
   DefaultMultiSelectStyle = [msControlSelect];
   DefaultTreeNodeHeight = 20;
+  DefaultTreeNodeExpandSignSize = 9;
 
 type
   TTreeViewExpandSignType = (
@@ -3545,7 +3546,7 @@ type
     property DefaultItemHeight: integer read FDefItemHeight write SetDefaultItemHeight default DefaultTreeNodeHeight;
     property DropTarget: TTreeNode read GetDropTarget write SetDropTarget;
     property ExpandSignColor: TColor read FExpandSignColor write FExpandSignColor default clWindowFrame;
-    property ExpandSignSize: integer read FExpandSignSize write FExpandSignSize;
+    property ExpandSignSize: integer read FExpandSignSize write FExpandSignSize default DefaultTreeNodeExpandSignSize;
     property ExpandSignType: TTreeViewExpandSignType
       read FExpandSignType write SetExpandSignType default tvestTheme;
     property InsertMarkNode: TTreeNode read FInsertMarkNode write SetInsertMarkNode;
diff --git a/lcl/include/treeview.inc b/lcl/include/treeview.inc
index f2f0cdfd7b..6987d6e541 100644
--- a/lcl/include/treeview.inc
+++ b/lcl/include/treeview.inc
@@ -4375,7 +4375,7 @@ begin
     FExpandSignSize := ThemeServices.GetDetailSize(Details).cx;
   end
   else
-    FExpandSignSize := 9;
+    FExpandSignSize := DefaultTreeNodeExpandSignSize;
 end;
 
 procedure TCustomTreeView.SetExpandSignType(Value: TTreeViewExpandSignType);