diff --git a/trees/construct_tree_inorder_preorder.py b/trees/construct_bt_inorder_preorder.py
similarity index 98%
rename from trees/construct_tree_inorder_preorder.py
rename to trees/construct_bt_inorder_preorder.py
index 765f32a..2f1518d 100644
--- a/trees/construct_tree_inorder_preorder.py
+++ b/trees/construct_bt_inorder_preorder.py
@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 # author: bt3gl
 
-def build_tree(preorder: list[int], inorder: list[int]) -> Optional[TreeNode]:
+def build_tree(preorder: list[int], inorder: list[int]) -> Optional[Node]:
         
         def helper(i_left, i_right, index_map):