diff --git a/app/e11sync/settings.py b/app/e11sync/settings.py
index 350b95b..f3f046d 100644
--- a/app/e11sync/settings.py
+++ b/app/e11sync/settings.py
@@ -34,8 +34,8 @@ if not environ.get("E11SYNC_DEBUG_PRINTED"):
     print("DATABASE_PATH={}".format(_DATABASE_PATH))
     environ["E11SYNC_DEBUG_PRINTED"] = "1"
 
-########################################
-## No more side effects after this place
+#######################################
+# No more side effects after this place
 
 SECRET_KEY = _SECRET_KEY
 
@@ -50,7 +50,7 @@ INTERNAL_IPS = ["127.0.0.1"]
 INSTALLED_APPS = (['debug_toolbar'] if DEBUG else []) + [
     'compressor',
     'signup.apps.SignupConfig',
- 
+
     'django.contrib.admin',
     'django.contrib.auth',
     'django.contrib.contenttypes',
diff --git a/app/e11sync/urls.py b/app/e11sync/urls.py
index 951d390..30d4255 100644
--- a/app/e11sync/urls.py
+++ b/app/e11sync/urls.py
@@ -22,6 +22,7 @@ from django.conf import settings
 urlpatterns = [
     path('admin/', admin.site.urls),
     ] + [
-        path("__debug__/", include("debug_toolbar.urls"))] if settings.DEBUG else [] + [
+        path("__debug__/", include("debug_toolbar.urls"))
+        ] if settings.DEBUG else [] + [
     path('', include('signup.urls')),
 ]
diff --git a/app/manage.py b/app/manage.py
index b5c8355..cbf2c82 100755
--- a/app/manage.py
+++ b/app/manage.py
@@ -3,6 +3,7 @@
 import os
 import sys
 
+
 def main():
     """Run administrative tasks."""
     os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'e11sync.settings')
diff --git a/app/signup/admin.py b/app/signup/admin.py
index 9949bce..c3582de 100644
--- a/app/signup/admin.py
+++ b/app/signup/admin.py
@@ -2,9 +2,16 @@ from django.contrib import admin
 
 from .models import Signup
 
+
 @admin.register(Signup)
 class SignupAdmin(admin.ModelAdmin):
-    _all_fields = ["email", "created_at", "anonymized_ip", "user_agent", "geoip"]
+    _all_fields = [
+        "email",
+        "created_at",
+        "anonymized_ip",
+        "user_agent",
+        "geoip"
+    ]
 
     date_hierarchy = "created_at"
     list_display = ["email", "created_at", "user_agent"] + ["place_name"]
diff --git a/app/signup/models.py b/app/signup/models.py
index 6bc4755..b7ee79d 100644
--- a/app/signup/models.py
+++ b/app/signup/models.py
@@ -1,15 +1,16 @@
 from django.db import models
 
+
 class Signup(models.Model):
     email = models.EmailField()
-    created_at = models.DateTimeField(auto_now_add = True)
+    created_at = models.DateTimeField(auto_now_add=True)
     anonymized_ip = models.GenericIPAddressField()
-    user_agent = models.CharField(max_length = 255)
-    geoip = models.JSONField(null = True, blank = True)
+    user_agent = models.CharField(max_length=255)
+    geoip = models.JSONField(null=True, blank=True)
 
     class Meta:
         constraints = [
-            models.UniqueConstraint(name = "unique_email", fields = ["email"]),
+            models.UniqueConstraint(name="unique_email", fields=["email"]),
         ]
 
     def __str__(self):
diff --git a/app/signup/tests.py b/app/signup/tests.py
index 2d93829..9655774 100644
--- a/app/signup/tests.py
+++ b/app/signup/tests.py
@@ -3,6 +3,7 @@ from django.urls import reverse
 
 from .models import Signup
 
+
 class SignupViewTest(TestCase):
     def setUp(self):
         self.client = Client()
@@ -14,9 +15,9 @@ class SignupViewTest(TestCase):
 
     def test_ok_signup(self):
         resp = self.client.post(reverse("index"), {"email": "foo@example.com"},
-                                follow = True,
-                                HTTP_USER_AGENT = "foo-agent",
-                                REMOTE_ADDR = "127.0.0.2")
+                                follow=True,
+                                HTTP_USER_AGENT="foo-agent",
+                                REMOTE_ADDR="127.0.0.2")
         self.assertEqual(resp.redirect_chain, [('/?success=subscribed', 302)])
         self.assertContains(resp, "You are now subscribed!")
         obj = Signup.objects.get()
diff --git a/app/signup/views.py b/app/signup/views.py
index 3e24669..7515d4b 100644
--- a/app/signup/views.py
+++ b/app/signup/views.py
@@ -31,10 +31,10 @@ def index(request):
             geoip = None
 
         s = Signup(
-          email = request.POST.get("email"),
-          anonymized_ip = anonymous_ip,
-          user_agent = request.META["HTTP_USER_AGENT"],
-          geoip = geoip,
+            email=request.POST.get("email"),
+            anonymized_ip=anonymous_ip,
+            user_agent=request.META["HTTP_USER_AGENT"],
+            geoip=geoip,
         )
 
         try:
@@ -42,7 +42,7 @@ def index(request):
         except ValidationError as e:
             print(e)
             return render(request, "signup/index.html",
-                            {"error_message": e.message})
+                          {"error_message": e.message})
 
         logging.info("registering email={}".format(request.POST.get("email")))
         try:
@@ -52,7 +52,7 @@ def index(request):
             return redirect(reverse("index") + "?success=already_subscribed")
         except DatabaseError:
             logger.exception("database error when registering an email")
-            err =  "Sorry, database error. Please come back later."
+            err = "Sorry, database error. Please come back later."
             return render(request, "signup/index.html",
                           {"error_message": err})
         return redirect(reverse("index") + "?success=subscribed")
diff --git a/flake.nix b/flake.nix
index e21a743..3513cdc 100644
--- a/flake.nix
+++ b/flake.nix
@@ -70,6 +70,12 @@
             statix.enable = true;
           };
         };
+        format = pkgs.runCommand "check-format" {} ''
+          ${pkgs.python3Packages.flake8}/bin/flake8 \
+              --max-line-length 99 \
+              --exclude ${./.}/app/signup/migrations/ ${./.}
+          mkdir -p $out
+        '';
       };
 
       apps.e11sync-gunicorn = {
@@ -83,12 +89,15 @@
 
       devShells.default = pkgs.mkShellNoCC {
         packages = with pkgs; [
-          python3Packages.django-debug-toolbar
           python3Packages.django_5
           python3Packages.django-compressor
           python3Packages.geoip2
           libmaxminddb
           dart-sass
+
+          python3Packages.django-debug-toolbar
+          python3Packages.flake8
+          python3Packages.autopep8
         ];
         GEOIP_PATH = "${geoip-archive}";
         E11SYNC_DEBUG = "1";