diff --git a/app.py b/app.py
index cbe40e23..c2bcca52 100644
--- a/app.py
+++ b/app.py
@@ -6,7 +6,7 @@
 from flask_sslify import SSLify
 
 DIR = os.path.dirname(os.path.realpath(__file__))
-ROOT = os.path.join(DIR, 'docs', '_build', 'html')
+ROOT = os.path.join(DIR, "docs", "_build", "html")
 
 
 def find_key(token):
@@ -21,20 +21,20 @@ def find_key(token):
 
 app = Flask(__name__)
 
-if 'DYNO' in os.environ:
-    sslify = SSLify(app, skips=['.well-known'])
+if "DYNO" in os.environ:
+    sslify = SSLify(app, skips=[".well-known"])
 
 
-@app.route('/<path:path>')
+@app.route("/<path:path>")
 def static_proxy(path):
     """Find static files."""
     return send_from_directory(ROOT, path)
 
 
-@app.route('/')
+@app.route("/")
 def index_redirection():
     """Redirecting index file."""
-    return send_from_directory(ROOT, 'index.html')
+    return send_from_directory(ROOT, "index.html")
 
 
 @app.route("/.well-known/acme-challenge/<token>")
diff --git a/app_test.py b/app_test.py
index f8a81328..53d3f0ee 100644
--- a/app_test.py
+++ b/app_test.py
@@ -7,12 +7,7 @@
 from werkzeug.exceptions import NotFound
 from flask_testing import LiveServerTestCase
 
-from app import (
-    acme,
-    find_key,
-    static_proxy,
-    index_redirection
-)
+from app import acme, find_key, static_proxy, index_redirection
 
 from app import ROOT
 from app import app
@@ -29,14 +24,14 @@ def create_app(self):
                 continue
             del os.environ[k]
 
-        self.token = 'token'
+        self.token = "token"
         self.key = "key"
-        os.environ['ACME_TOKEN'] = self.token
-        os.environ['ACME_KEY'] = self.key
-        os.environ['FLASK_ENV'] = 'development'
-        os.environ['FLASK_DEBUG'] = "1"
-        app.config['TESTING'] = True
-        app.config['LIVESERVER_PORT'] = 0
+        os.environ["ACME_TOKEN"] = self.token
+        os.environ["ACME_KEY"] = self.key
+        os.environ["FLASK_ENV"] = "development"
+        os.environ["FLASK_DEBUG"] = "1"
+        app.config["TESTING"] = True
+        app.config["LIVESERVER_PORT"] = 0
         return app
 
     def test_index_redirection_req(self):
@@ -47,21 +42,21 @@ def test_index_redirection_req(self):
 
     def test_static_proxy_req(self):
         """Test that send a request for notes."""
-        htmls = os.listdir(os.path.join(ROOT, 'notes'))
+        htmls = os.listdir(os.path.join(ROOT, "notes"))
         url = self.get_server_url()
         for h in htmls:
-            u = url + '/notes/' + h
+            u = url + "/notes/" + h
             resp = requests.get(u)
             self.assertEqual(resp.status_code, 200)
 
     def test_acme_req(self):
         """Test that send a request for a acme key."""
         url = self.get_server_url()
-        u = url + '/.well-known/acme-challenge/token'
+        u = url + "/.well-known/acme-challenge/token"
         resp = requests.get(u)
         self.assertEqual(resp.status_code, 200)
 
-        u = url + '/.well-known/acme-challenge/foo'
+        u = url + "/.well-known/acme-challenge/foo"
         resp = requests.get(u)
         self.assertEqual(resp.status_code, 404)
 
@@ -71,15 +66,15 @@ def test_find_key(self):
         key = self.key
         self.assertEqual(find_key(token), key)
 
-        del os.environ['ACME_TOKEN']
-        del os.environ['ACME_KEY']
+        del os.environ["ACME_TOKEN"]
+        del os.environ["ACME_KEY"]
 
-        os.environ['ACME_TOKEN_ENV'] = token
-        os.environ['ACME_KEY_ENV'] = key
+        os.environ["ACME_TOKEN_ENV"] = token
+        os.environ["ACME_KEY_ENV"] = key
         self.assertEqual(find_key(token), key)
 
-        del os.environ['ACME_TOKEN_ENV']
-        del os.environ['ACME_KEY_ENV']
+        del os.environ["ACME_TOKEN_ENV"]
+        del os.environ["ACME_KEY_ENV"]
 
     def test_acme(self):
         """Test that send a request for a acme key."""
@@ -89,12 +84,12 @@ def test_acme(self):
 
         token = token + "_env"
         key = key + "_env"
-        os.environ['ACME_TOKEN_ENV'] = token
-        os.environ['ACME_KEY_ENV'] = key
+        os.environ["ACME_TOKEN_ENV"] = token
+        os.environ["ACME_KEY_ENV"] = key
         self.assertEqual(find_key(token), key)
 
-        del os.environ['ACME_TOKEN_ENV']
-        del os.environ['ACME_KEY_ENV']
+        del os.environ["ACME_TOKEN_ENV"]
+        del os.environ["ACME_KEY_ENV"]
 
         self.assertRaises(NotFound, acme, token)
 
@@ -106,10 +101,10 @@ def test_index_redirection(self):
 
     def test_static_proxy(self):
         """Test that request static pages."""
-        htmls = os.listdir(os.path.join(ROOT, 'notes'))
+        htmls = os.listdir(os.path.join(ROOT, "notes"))
 
         for h in htmls:
-            u = 'notes/' + h
+            u = "notes/" + h
             resp = static_proxy(u)
             self.assertEqual(resp.status_code, 200)
             resp.close()