diff --git a/stregsystem/admin.py b/stregsystem/admin.py
index 74a5ab7d..80f4f4dd 100644
--- a/stregsystem/admin.py
+++ b/stregsystem/admin.py
@@ -202,7 +202,7 @@ class Meta:
     def clean_username(self):
         username = self.cleaned_data['username']
         if self.instance is None or self.instance.pk is None:
-            if Member.objects.filter(username=username).exists():
+            if Member.objects.filter(username__iexact=username).exists():
                 raise forms.ValidationError("Brugernavnet er allerede taget")
         return username
 
@@ -234,7 +234,7 @@ class MemberAdmin(admin.ModelAdmin):
 
     def save_model(self, request, obj, form, change):
         if 'username' in form.changed_data and change:
-            if Member.objects.filter(username=obj.username).exclude(pk=obj.pk).exists():
+            if Member.objects.filter(username__iexact=obj.username).exclude(pk=obj.pk).exists():
                 messages.add_message(request, messages.WARNING, 'Det brugernavn var allerede optaget')
         super().save_model(request, obj, form, change)
 
diff --git a/stregsystem/tests.py b/stregsystem/tests.py
index b2db8a45..fd64bcb5 100644
--- a/stregsystem/tests.py
+++ b/stregsystem/tests.py
@@ -964,6 +964,11 @@ def test_cant_create_duplicate_username(self):
         form = MemberForm(model_to_dict(jeff))
         self.assertFalse(form.is_valid())
 
+    def test_cant_create_duplicate_username_in_other_case(self):
+        jeff = Member(username="JeFf", firstname="jeffrey", lastname="jefferson", gender="M")
+        form = MemberForm(model_to_dict(jeff))
+        self.assertFalse(form.is_valid())
+
     def test_can_create_non_duplicate_username(self):
         not_jeff = Member(username="not_jeff", firstname="jeff", lastname="jefferson", gender="M")
         form = MemberForm(model_to_dict(not_jeff))