diff --git a/src/chilife/io.py b/src/chilife/io.py
index 92531d0..8988ca7 100644
--- a/src/chilife/io.py
+++ b/src/chilife/io.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from typing import Tuple, Dict, Union, BinaryIO, TextIO
 import textwrap
 import warnings