diff --git a/openmc/weight_windows.py b/openmc/weight_windows.py
index 6e718b858..64d2c5100 100644
--- a/openmc/weight_windows.py
+++ b/openmc/weight_windows.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
-
 from collections.abc import Iterable
 from numbers import Real, Integral
+from typing import Iterable, List
 
 from xml.etree import ElementTree as ET
 import numpy as np