diff --git a/data_structures/binary_tree/binary_tree_mirror.py b/data_structures/binary_tree/binary_tree_mirror.py
index dc7f657b3..cdd56e35d 100644
--- a/data_structures/binary_tree/binary_tree_mirror.py
+++ b/data_structures/binary_tree/binary_tree_mirror.py
@@ -1,6 +1,6 @@
 """
 Problem Description:
-Given a binary tree, return it's mirror.
+Given a binary tree, return its mirror.
 """