diff --git a/sync_pre_commit_deps.py b/sync_pre_commit_deps.py
index fdc28ec..9897087 100644
--- a/sync_pre_commit_deps.py
+++ b/sync_pre_commit_deps.py
@@ -47,7 +47,7 @@ def main(argv: Sequence[str] | None = None) -> int:
     yaml.preserve_quotes = True
     yaml.indent(yaml_mapping, yaml_sequence, yaml_offset)
 
-    with open(filename) as f:
+    with open(filename, encoding='utf-8') as f:
         loaded = yaml.load(f)
 
     # TODO - validate schema?
diff --git a/tests/sync_pre_commit_deps_test.py b/tests/sync_pre_commit_deps_test.py
index 8f5517a..c12c13d 100644
--- a/tests/sync_pre_commit_deps_test.py
+++ b/tests/sync_pre_commit_deps_test.py
@@ -35,15 +35,25 @@
             '        -   mypy==0.123\n',
             id='local hook shadows supported lib',
         ),
+        pytest.param(
+            'repos:\n'
+            '-   repo: https://github.com/psf/black\n'
+            '    rev: 23.3.0\n'
+            '    hooks:\n'
+            '    -   name: \N{SNOWMAN} black\n'
+            '        id: black\n',
+            id='unicode no-op',
+        ),
     ),
 )
 def test_main_noop(tmpdir, s):
     cfg = tmpdir.join('.pre-commit-config.yaml')
-    cfg.write(s)
+    cfg.write_binary(s.encode())
 
     assert not main((str(cfg),))
 
-    assert cfg.read() == s
+    with open(cfg, encoding='utf-8') as f:
+        assert f.read() == s
 
 
 def test_main_writes_all(tmpdir):