diff --git a/importlib_resources/tests/test_files.py b/importlib_resources/tests/test_files.py
index bca626c..f45a229 100644
--- a/importlib_resources/tests/test_files.py
+++ b/importlib_resources/tests/test_files.py
@@ -163,7 +163,9 @@ def _compile_importlib(self):
         sources = pathlib.Path(resources.__file__).parent
 
         for source_path in sources.glob('**/*.py'):
-            c_path = c_resources.joinpath(source_path.relative_to(sources)).with_suffix('.pyc')
+            c_path = c_resources.joinpath(source_path.relative_to(sources)).with_suffix(
+                '.pyc'
+            )
             py_compile.compile(source_path, c_path)
         self.fixtures.enter_context(import_helper.DirsOnSysPath(bin_site))