diff --git a/epi_judge_python_solutions/lowest_common_ancestor_with_parent.py b/epi_judge_python_solutions/lowest_common_ancestor_with_parent.py
index c7eae6b37..62270ede2 100644
--- a/epi_judge_python_solutions/lowest_common_ancestor_with_parent.py
+++ b/epi_judge_python_solutions/lowest_common_ancestor_with_parent.py
@@ -12,7 +12,7 @@ def lca(node0: BinaryTreeNode,
         node1: BinaryTreeNode) -> Optional[BinaryTreeNode]:
     def get_depth(node):
         depth = 0
-        while node:
+        while node.parent:
             depth += 1
             node = node.parent
         return depth