diff --git a/lcl/interfaces/carbon/carbondef.pp b/lcl/interfaces/carbon/carbondef.pp
index fb11b0c266..e948ec0a59 100644
--- a/lcl/interfaces/carbon/carbondef.pp
+++ b/lcl/interfaces/carbon/carbondef.pp
@@ -31,7 +31,7 @@ uses
   MacOSAll,
   // wdgetset
   WSLCLClasses, Classes, SysUtils, Controls, LCLType, LCLProc, Graphics, Contnrs,
-  AVL_Tree, LMessages, LCLMessageGlue;
+  Laz_AVL_Tree, LMessages, LCLMessageGlue;
 
 var
   LAZARUS_FOURCC: FourCharCode;    // = 'Laz ';
@@ -348,7 +348,11 @@ function RegisterObjectEventHandler(AHandler: TCarbonObjectEventHandlerProc): Ev
 var
   Node: TUPPAVLTreeNode;
 begin
-  if UPPTree = nil then UPPTree := TAVLTree.Create;
+  if UPPTree = nil then
+  begin
+    UPPTree := TAVLTree.Create;
+    UPPTree.NodeClass:=TUPPAVLTreeNode;
+  end;
 
   Node := TUPPAVLTreeNode(UPPTree.Find(AHandler));
   if Node = nil then