diff --git a/shiftregister/app/models.py b/shiftregister/app/models.py
index 68435de..2e80da6 100644
--- a/shiftregister/app/models.py
+++ b/shiftregister/app/models.py
@@ -77,7 +77,8 @@ class ShiftRegistration(models.Model):
 
     def can_cancel(self):
         return self.shift.start_at > (
-            timezone.now() + global_preferences_registry.manager()["helper__min_cancel_time"]
+            timezone.now()
+            + global_preferences_registry.manager()["helper__min_cancel_time"]
         )
 
     def send_reminder(self):
diff --git a/shiftregister/app/views.py b/shiftregister/app/views.py
index e2159e2..0a97207 100644
--- a/shiftregister/app/views.py
+++ b/shiftregister/app/views.py
@@ -178,6 +178,13 @@ def shift(request, shiftid):
                     "Bitte bestätige zuerst deine Telefonnummer",
                 )
                 return redirect("shift", shiftid=shift.pk)
+            if shift.deleted:
+                messages.add_message(
+                    request,
+                    messages.ERROR,
+                    "Diese Schicht wurde gelöscht.",
+                )
+                return redirect("index")
             if context["can_register"]:
                 s = ShiftRegistration(helper=helper, shift=shift)
                 s.save()
diff --git a/shiftregister/settings.py b/shiftregister/settings.py
index 320ad19..e56c8a1 100644
--- a/shiftregister/settings.py
+++ b/shiftregister/settings.py
@@ -15,6 +15,7 @@ from os import getenv
 import sentry_sdk
 from sentry_sdk.integrations.celery import CeleryIntegration
 from sentry_sdk.integrations.django import DjangoIntegration
+from django.contrib.messages import constants as messages
 
 # Build paths inside the project like this: BASE_DIR / 'subdir'.
 BASE_DIR = Path(__file__).resolve().parent.parent
@@ -166,3 +167,7 @@ if getenv("SENTRY_DSN"):
     )
 
 PHONENUMBER_DEFAULT_REGION = "DE"
+
+MESSAGE_TAGS = {
+    messages.ERROR: "danger",
+}