diff --git a/sorts/pancake_sort.py b/sorts/pancake_sort.py
index e5d600738435..b6c198acc03c 100644
--- a/sorts/pancake_sort.py
+++ b/sorts/pancake_sort.py
@@ -9,7 +9,7 @@
 """
 
 
-def pancake_sort(arr):
+def pancake_sort(arr: list) -> list:
     """Sort Array with Pancake Sort.
     :param arr: Collection containing comparable items
     :return: Collection ordered in ascending order of items