diff --git a/doorcontrol/admin.py b/doorcontrol/admin.py
index 15b7611..2f0b038 100644
--- a/doorcontrol/admin.py
+++ b/doorcontrol/admin.py
@@ -11,41 +11,24 @@ class DoorAdmin(admin.ModelAdmin):
     pass
 
 
-class IsRedFilter(admin.SimpleListFilter):
-    title = "Is Red"
-    parameter_name = "is_red"
-
-    def lookups(self, request, model_admin):
-        return (
-            ("1", "Yes"),
-            ("0", "No"),
-        )
-
-    def queryset(self, request, queryset):
-        if self.value() is None:
-            return queryset
-        else:
-            return queryset.filter(is_red=(self.value() == "1"))
-
-
 @admin.register(HIDEvent)
 class HIDEventAdmin(DjangoObjectActions, admin.ModelAdmin):
     search_fields = ["forename", "surname", "cardholder_id"]
-    list_display = ["timestamp", "door", "event_type", "description", "is_red"]
+    list_display = ["timestamp", "door", "event_type", "description", "_is_red"]
     list_filter = [
         "timestamp",
         "door",
         "event_type",
-        IsRedFilter,
+        "is_red",
     ]
     readonly_fields = ["decoded_card_number"]
     changelist_actions = ("refresh_all_doors",)
 
     def get_queryset(self, request):
-        return super().get_queryset(request).with_is_red().with_decoded_card_number()
+        return super().get_queryset(request).with_decoded_card_number()
 
     @admin.display(boolean=True)
-    def is_red(self, obj):
+    def _is_red(self, obj):
         return obj.is_red
 
     def has_add_permission(self, request, obj=None):
diff --git a/doorcontrol/migrations/0004_hidevent_is_red.py b/doorcontrol/migrations/0004_hidevent_is_red.py
new file mode 100644
index 0000000..8fbcdb4
--- /dev/null
+++ b/doorcontrol/migrations/0004_hidevent_is_red.py
@@ -0,0 +1,40 @@
+# Generated by Django 5.0 on 2023-12-04 16:53
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("doorcontrol", "0003_door_ip"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="hidevent",
+            name="is_red",
+            field=models.GeneratedField(
+                db_persist=False,
+                expression=models.Q(
+                    (
+                        "event_type__in",
+                        [
+                            1022,
+                            1023,
+                            2024,
+                            2029,
+                            2036,
+                            2042,
+                            2043,
+                            2046,
+                            4041,
+                            4042,
+                            4043,
+                            4044,
+                            4045,
+                        ],
+                    )
+                ),
+                output_field=models.BooleanField(),
+            ),
+        ),
+    ]
diff --git a/doorcontrol/models.py b/doorcontrol/models.py
index 62207b6..39031a0 100644
--- a/doorcontrol/models.py
+++ b/doorcontrol/models.py
@@ -2,7 +2,7 @@ from datetime import datetime
 
 from django.conf import settings
 from django.db import models
-from django.db.models import ExpressionWrapper, F, Func, Q
+from django.db.models import F, Func, Q
 from django.db.models.functions import Mod
 from django.utils import timezone
 
@@ -26,31 +26,6 @@ class Door(models.Model):
 
 
 class HIDEventQuerySet(models.QuerySet):
-    def with_is_red(self):
-        """Based on `function isRedEvent` from /html/hid-global.js on a HID EDGE EVO Solo"""
-        return self.annotate(
-            is_red=ExpressionWrapper(
-                Q(
-                    event_type__in=[
-                        HIDEvent.EventType.DENIED_ACCESS_CARD_NOT_FOUND,
-                        HIDEvent.EventType.DENIED_ACCESS_ACCESS_PIN_NOT_FOUND,
-                        HIDEvent.EventType.DENIED_ACCESS_SCHEDULE,
-                        HIDEvent.EventType.DENIED_ACCESS_WRONG_PIN,
-                        HIDEvent.EventType.DENIED_ACCESS_CARD_EXPIRED,
-                        HIDEvent.EventType.DENIED_ACCESS_PIN_LOCKOUT,
-                        HIDEvent.EventType.DENIED_ACCESS_UNASSIGNED_CARD,
-                        HIDEvent.EventType.DENIED_ACCESS_PIN_EXPIRED,
-                        HIDEvent.EventType.DOOR_FORCED_ALARM,
-                        HIDEvent.EventType.DOOR_HELD_ALARM,
-                        HIDEvent.EventType.TAMPER_SWITCH_ALARM,
-                        HIDEvent.EventType.AC_FAILURE,
-                        HIDEvent.EventType.BATTERY_FAILURE,
-                    ]
-                ),
-                output_field=models.BooleanField(),
-            )
-        )
-
     def with_decoded_card_number(self):
         # TODO: CONV and BIT_COUNT are MySQL/MariaDB specific
         class Conv(Func):
@@ -137,6 +112,29 @@ class HIDEvent(models.Model):
         max_length=8, blank=True, null=True, db_column="rawCardNumber"
     )
 
+    # Based on `function isRedEvent` from /html/hid-global.js on a HID EDGE EVO Solo
+    is_red = models.GeneratedField(
+        expression=Q(
+            event_type__in=[
+                EventType.DENIED_ACCESS_CARD_NOT_FOUND,
+                EventType.DENIED_ACCESS_ACCESS_PIN_NOT_FOUND,
+                EventType.DENIED_ACCESS_SCHEDULE,
+                EventType.DENIED_ACCESS_WRONG_PIN,
+                EventType.DENIED_ACCESS_CARD_EXPIRED,
+                EventType.DENIED_ACCESS_PIN_LOCKOUT,
+                EventType.DENIED_ACCESS_UNASSIGNED_CARD,
+                EventType.DENIED_ACCESS_PIN_EXPIRED,
+                EventType.DOOR_FORCED_ALARM,
+                EventType.DOOR_HELD_ALARM,
+                EventType.TAMPER_SWITCH_ALARM,
+                EventType.AC_FAILURE,
+                EventType.BATTERY_FAILURE,
+            ]
+        ),
+        output_field=models.BooleanField(),
+        db_persist=False,
+    )
+
     @classmethod
     def from_xml_attributes(cls, door: Door, attrib: dict[str:str]):
         field_lookup = {