diff --git a/trees/bt_height.py b/trees/bt_height.py
index 65fa688..bb16d53 100644
--- a/trees/bt_height.py
+++ b/trees/bt_height.py
@@ -3,7 +3,9 @@
 # author: bt3gl
 
 def height(root):
+      
       if not root:
-            return -1
+            return 0
+            
       return 1 + max(height(root.left), height(root.right))