diff --git a/tests/test_proxy_functional.py b/tests/test_proxy_functional.py
index 1acf3acf948..5844783f29b 100644
--- a/tests/test_proxy_functional.py
+++ b/tests/test_proxy_functional.py
@@ -15,7 +15,7 @@
 @pytest.fixture
 def trustme_certs(tmp_path):
     ca = trustme.CA()
-    ca.issue_cert(u"localhost")
+    ca.issue_cert("localhost")
     ca_cert_path = tmp_path / "ca.pem"
     ca.cert_pem.write_to_path(ca_cert_path)
     ca_key_path = tmp_path / "server.key"
@@ -27,12 +27,17 @@ def trustme_certs(tmp_path):
 def secure_proxy_url(trustme_certs):
     port = proxy.common.utils.get_available_port()
     input_args = [
-        '--num-workers', '1',
-        '--threadless',
-        '--hostname', '0.0.0.0',
-        '--port', str(port),
-        '--cert-file', trustme_certs[0],
-        '--key-file', trustme_certs[1],
+        "--num-workers",
+        "1",
+        "--threadless",
+        "--hostname",
+        "0.0.0.0",
+        "--port",
+        str(port),
+        "--cert-file",
+        trustme_certs[0],
+        "--key-file",
+        trustme_certs[1],
     ]
     proxy_url = "http://0.0.0.0:" + str(port)
     with proxy.Proxy(input_args=input_args) as proxy_instance: