diff --git a/pre_commit_hooks/check_merge_conflict.py b/pre_commit_hooks/check_merge_conflict.py
index aed1e9c..22031a2 100644
--- a/pre_commit_hooks/check_merge_conflict.py
+++ b/pre_commit_hooks/check_merge_conflict.py
@@ -1,6 +1,7 @@
+from __future__ import annotations
+
 import argparse
 import os.path
-from typing import Optional
 from typing import Sequence
 
 from pre_commit_hooks.util import cmd_output
@@ -26,7 +27,7 @@
     )
 
 
-def main(argv: Optional[Sequence[str]] = None) -> int:
+def main(argv: Sequence[str] | None = None) -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument('filenames', nargs='*')
     parser.add_argument('--assume-in-merge', action='store_true')