diff --git a/tests/test_traefik.py b/tests/test_traefik.py
index cd7d251..f950266 100644
--- a/tests/test_traefik.py
+++ b/tests/test_traefik.py
@@ -254,5 +254,5 @@ def test_listen_address(tmpdir, tljh_dir):
     traefik.ensure_traefik_config(str(state_dir))
 
     cfg = _read_static_config(state_dir)
-    assert cfg["entryPoints"]['http']['address'] == "127.0.0.1:80"
-    assert cfg["entryPoints"]['https']['address'] == "127.0.0.1:443"
+    assert cfg["entryPoints"]["http"]["address"] == "127.0.0.1:80"
+    assert cfg["entryPoints"]["https"]["address"] == "127.0.0.1:443"
diff --git a/tljh/config.py b/tljh/config.py
index 0bb3921..d308e9e 100644
--- a/tljh/config.py
+++ b/tljh/config.py
@@ -248,8 +248,8 @@ def check_hub_ready():
     http_port = load_config()["http"]["port"]
     # The default config is an empty address, so it binds on all interfaces.
     # Test the connectivity on the local address.
-    if http_address == '':
-        http_address = '127.0.0.1'
+    if http_address == "":
+        http_address = "127.0.0.1"
     try:
         r = requests.get(
             "http://%s:%d%s/hub/api" % (http_address, http_port, base_url), verify=False