diff --git a/deploy/check_home_seo.py b/deploy/check_home_seo.py
index 07ba705f..c585b3cf 100644
--- a/deploy/check_home_seo.py
+++ b/deploy/check_home_seo.py
@@ -1,6 +1,5 @@
 """Verify homepage metadata without changing Markdown or non-home resources."""
-from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
-from pathlib import Path
+
 import socket
 import subprocess
 import tempfile
@@ -8,9 +7,13 @@
 import time
 import urllib.error
 import urllib.request
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
+from pathlib import Path
 
 HTML = b'<!doctype html><html><head><title>msg</title></head><body>Public home</body></html>'
 MARKDOWN = b'# msg\n\nAgent-readable public home.\n'
+
+
 class Backend(BaseHTTPRequestHandler):
     def do_GET(self):
         browser = 'text/html' in self.headers.get('Accept', '')
@@ -19,41 +22,58 @@ def do_GET(self):
         self.send_header('Content-Security-Policy', "default-src 'none'")
         self.end_headers()
         self.wfile.write(HTML if browser else MARKDOWN)
+
     def log_message(self, *args):
         pass
+
+
 backend = ThreadingHTTPServer(('127.0.0.1', 0), Backend)
 thread = threading.Thread(target=backend.serve_forever, daemon=True)
 thread.start()
 with socket.socket() as sock:
     sock.bind(('127.0.0.1', 0))
     port = sock.getsockname()[1]
+
+
 def get(path, accept):
-    with urllib.request.urlopen(urllib.request.Request(
-        f'http://127.0.0.1:{port}{path}', headers={'Accept': accept}), timeout=3) as response:
+    with urllib.request.urlopen(
+        urllib.request.Request(f'http://127.0.0.1:{port}{path}', headers={'Accept': accept}),
+        timeout=3,
+    ) as response:
         return response.headers, response.read()
+
+
 try:
     with tempfile.TemporaryDirectory(prefix='msg-home-seo-') as temp:
         directory = Path(temp)
         conf = directory / 'nginx.conf'
         snippet = Path(__file__).with_name('nginx-home-seo.conf').read_text()
-        conf.write_text(f'pid {directory}/nginx.pid; error_log {directory}/error.log; daemon off; master_process off; events {{}}\n'
-                        'http { access_log off;\n'
-                        + ''.join(f'{kind}_temp_path {directory}/{kind};\n' for kind in ['client_body','proxy','fastcgi','uwsgi','scgi'])
-                        + f'upstream msg_lmm_best {{ server 127.0.0.1:{backend.server_port}; }}\n'
-                        'map $uri $msg_browser_cache_control { default "private, no-cache"; }\n'
-                        'map $uri $msg_browser_referrer_policy { default "no-referrer"; }\n'
-                        + f'server {{ listen 127.0.0.1:{port};\n' + snippet
-                        + 'location / { proxy_pass http://msg_lmm_best; }\n}}\n')
-        process = subprocess.Popen(['nginx', '-p', temp, '-c', str(conf)], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        conf.write_text(
+            f'pid {directory}/nginx.pid; error_log {directory}/error.log; daemon off; master_process off; events {{}}\n'
+            'http { access_log off;\n'
+            + ''.join(
+                f'{kind}_temp_path {directory}/{kind};\n'
+                for kind in ['client_body', 'proxy', 'fastcgi', 'uwsgi', 'scgi']
+            )
+            + f'upstream msg_lmm_best {{ server 127.0.0.1:{backend.server_port}; }}\n'
+            'map $uri $msg_browser_cache_control { default "private, no-cache"; }\n'
+            'map $uri $msg_browser_referrer_policy { default "no-referrer"; }\n'
+            + f'server {{ listen 127.0.0.1:{port};\n'
+            + snippet
+            + 'location / { proxy_pass http://msg_lmm_best; }\n}}\n'
+        )
+        process = subprocess.Popen(
+            ['nginx', '-p', temp, '-c', str(conf)], stdout=subprocess.PIPE, stderr=subprocess.PIPE
+        )
         try:
-            for attempt in range(40):
+            for _attempt in range(40):
                 try:
                     get('/', 'text/html')
                     break
                 except urllib.error.URLError:
                     if process.poll() is not None:
-                        raise RuntimeError(process.communicate()[1].decode())
-                    time.sleep(.05)
+                        raise RuntimeError(process.communicate()[1].decode()) from None
+                    time.sleep(0.05)
             else:
                 raise RuntimeError('Nginx did not start')
             headers, body = get('/', 'text/html')
@@ -64,7 +84,9 @@ def get(path, accept):
             headers, body = get('/', 'text/markdown')
             assert body == MARKDOWN and headers['Content-Type'].startswith('text/markdown')
             assert get('/another-resource', 'text/html')[1] == HTML
-            print('HTML metadata, canonical header, CSP/cache, unchanged Markdown and other resources passed')
+            print(
+                'HTML metadata, canonical header, CSP/cache, unchanged Markdown and other resources passed'
+            )
         finally:
             if process.poll() is None:
                 process.terminate()