diff --git a/schoeffelbe/pr04.py b/schoeffelbe/pr04.py
index a66f210..25d3f2c 100644
--- a/schoeffelbe/pr04.py
+++ b/schoeffelbe/pr04.py
@@ -157,7 +157,7 @@ class BinaryTreeNode(MemoryCell):
     def __str__(self):
         return str(self.value)
 
-class BinaryTree(BinaryTreeNode):
+class BinaryTree:
     def __init__(self): 
         self.root: BinaryTreeNode | None = None