diff --git a/pre_commit_hooks/trailing_whitespace_fixer.py b/pre_commit_hooks/trailing_whitespace_fixer.py
index 20a4ced..fc6dc86 100644
--- a/pre_commit_hooks/trailing_whitespace_fixer.py
+++ b/pre_commit_hooks/trailing_whitespace_fixer.py
@@ -30,7 +30,7 @@ def _process_line(
         is_markdown: bool,
         chars: bytes | None,
         line_num: int,
-        error_lines: list[int] | None
+        error_lines: list[int] | None,
 ) -> bytes:
     org_line = line
     if line[-2:] == b'\r\n':
@@ -46,7 +46,7 @@ def _process_line(
         return line[:-2].rstrip(chars) + b'  ' + eol
     result = line.rstrip(chars) + eol
     if error_lines is not None and org_line != result:
-        error_lines.append(line_num+1)
+        error_lines.append(line_num + 1)
     return result
 
 
@@ -106,8 +106,8 @@ def main(argv: Sequence[str] | None = None) -> int:
         error_lines = []
         if _fix_file(filename, md, chars, args.check, error_lines):
             if args.check:
-                location = ",".join(map(str, error_lines[:4]))
-                location += "..." if len(error_lines) > 4 else ""
+                location = ','.join(map(str, error_lines[:4]))
+                location += '...' if len(error_lines) > 4 else ''
                 print(f'Trailing whitespace check failed: {filename} @ {location}')
             else:
                 print(f'Fixing {filename}')
diff --git a/tests/end_of_file_fixer_test.py b/tests/end_of_file_fixer_test.py
index a5349d5..db6ef35 100644
--- a/tests/end_of_file_fixer_test.py
+++ b/tests/end_of_file_fixer_test.py
@@ -44,7 +44,7 @@ def test_fix_file(input_s, expected_retval, output, options):
         options = [options]
 
     file_obj = io.BytesIO(input_s)
-    ret = fix_file(file_obj, "--check" in [*options])
+    ret = fix_file(file_obj, '--check' in [*options])
     assert file_obj.getvalue() == output
     assert ret == expected_retval
 
diff --git a/tests/trailing_whitespace_fixer_test.py b/tests/trailing_whitespace_fixer_test.py
index fc221e2..949d420 100644
--- a/tests/trailing_whitespace_fixer_test.py
+++ b/tests/trailing_whitespace_fixer_test.py
@@ -18,21 +18,22 @@ def test_fixes_trailing_whitespace(input_s, expected, tmpdir):
     assert main((str(path),)) == 1
     assert path.read() == expected
 
+
 @pytest.mark.parametrize(
-    ('input_s', 'exit_code', "lines"),
+    ('input_s', 'exit_code', 'lines'),
     (
-            ('foo \nbar \n', 1, [1,2]),
-            ('bar\t\nbaz\t\n', 1, [1,2]),
-            ('bar\nbaz\t\n', 1, [2]),
+        ('foo \nbar \n', 1, [1, 2]),
+        ('bar\t\nbaz\t\n', 1, [1, 2]),
+        ('bar\nbaz\t\n', 1, [2]),
     ),
 )
 def test_fixes_trailing_whitespace_check_only(capsys, input_s, exit_code, lines, tmpdir):
     path = tmpdir.join('file.md')
     path.write(input_s)
-    assert main(('--check', str(path),)) == exit_code
+    assert main(('--check', str(path))) == exit_code
     assert path.read() == input_s
     captured = capsys.readouterr()
-    location = "@ " + ','.join(map(str, lines))
+    location = '@ ' + ','.join(map(str, lines))
     assert location in captured.out