diff --git a/inyoka/portal/migrations/0036_user_upper_username_idx.py b/inyoka/portal/migrations/0036_user_upper_username_idx.py
new file mode 100644
index 000000000..d24d3e286
--- /dev/null
+++ b/inyoka/portal/migrations/0036_user_upper_username_idx.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.2.23 on 2024-02-05 21:55
+
+from django.db import migrations, models
+import django.db.models.functions.text
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('portal', '0035_auto_20231127_0114'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='user',
+            index=models.Index(django.db.models.functions.text.Upper('username'), name='upper_username_idx'),
+        ),
+    ]
diff --git a/inyoka/portal/user.py b/inyoka/portal/user.py
index bbaf642d3..036d38db3 100644
--- a/inyoka/portal/user.py
+++ b/inyoka/portal/user.py
@@ -24,6 +24,7 @@
 from django.core.cache import cache
 from django.core.exceptions import ValidationError
 from django.db import models, transaction
+from django.db.models.functions import Upper
 from django.dispatch import receiver
 from django.utils.html import escape
 from django.utils.translation import gettext as _
@@ -547,6 +548,9 @@ class Meta:
         permissions = (
             ('subscribe_user', 'Can subscribe Users'),
         )
+        indexes = [
+            models.Index(Upper('username'), name='upper_username_idx'),
+        ]
 
 
 class UserPage(models.Model):