diff --git a/c3l_membership/__init__.py b/c3l_membership/__init__.py
--- a/c3l_membership/__init__.py
+++ b/c3l_membership/__init__.py
@@ -18,10 +18,11 @@ def create_app():
 
     app = Flask(__name__)
 
-    if app.debug:
-        config_file = os.path.abspath("config.json")
-    else:
-        config_file = os.path.abspath("/etc/membership.json")
+    config_file = (
+        os.path.abspath("config.json")
+        if app.debug
+        else os.path.abspath("/etc/membership.json")
+    )
 
     try:
         app.config.from_file(config_file, load=json.load)
diff --git a/c3l_membership/forms.py b/c3l_membership/forms.py
--- a/c3l_membership/forms.py
+++ b/c3l_membership/forms.py
@@ -1,5 +1,3 @@
-from datetime import date
-
 from flask_babel import lazy_gettext
 from flask_wtf import FlaskForm
 from wtforms import (
@@ -60,10 +58,12 @@ class MembershipForm(FlaskForm):
             Length(max=255),
         ],
     )
+
     email = StringField(
         lazy_gettext("E-Mail"),
         validators=[InputRequired(lazy_gettext("This field is required!")), Email()],
     )
+
     fullname = StringField(
         lazy_gettext("Full Name"),
         validators=[
@@ -123,6 +123,7 @@ class MembershipForm(FlaskForm):
         lazy_gettext("Nr., Street"),
         validators=[Optional(), Length(max=4000)],
     )
+
     zip = StringField(
         lazy_gettext("Postal Code"),
         validators=[Optional(), Length(max=30)],