diff --git a/test/test_0_basic.py b/test/test_0_basic.py
index 9c3e1588..e44058a9 100644
--- a/test/test_0_basic.py
+++ b/test/test_0_basic.py
@@ -71,8 +71,8 @@ def test_allow_empty(tmp_path, build_frontend_env):
 
     # build the wheels
     actual_wheels = utils.cibuildwheel_run(
-        project_dir, add_env=build_frontend_env,
-        add_args=["--allow-empty"])
+        project_dir, add_env=build_frontend_env, add_args=["--allow-empty"]
+    )
 
     # check that the expected wheels are produced
     expected_wheels = utils.expected_wheels("spam", "0.1.0")
diff --git a/test/utils.py b/test/utils.py
index 1e5bbca6..648794bd 100644
--- a/test/utils.py
+++ b/test/utils.py
@@ -44,7 +44,9 @@ def cibuildwheel_get_build_identifiers(project_path, env=None, *, prerelease_pyt
     return cmd_output.strip().split("\n")
 
 
-def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, output_dir=None, add_args=None):
+def cibuildwheel_run(
+    project_path, package_dir=".", env=None, add_env=None, output_dir=None, add_args=None
+):
     """
     Runs cibuildwheel as a subprocess, building the project at project_path.
 
@@ -81,7 +83,8 @@ def cibuildwheel_run(project_path, package_dir=".", env=None, add_env=None, outp
                 "--output-dir",
                 str(output_dir or tmp_output_dir),
                 str(package_dir),
-            ] + add_args,
+            ]
+            + add_args,
             env=env,
             cwd=project_path,
             check=True,