diff --git a/modoboa/admin/api/v2/serializers.py b/modoboa/admin/api/v2/serializers.py
index cf0dd9dfa..e91553128 100644
--- a/modoboa/admin/api/v2/serializers.py
+++ b/modoboa/admin/api/v2/serializers.py
@@ -543,7 +543,7 @@ class WritableAccountSerializer(v1_serializers.WritableAccountSerializer):
         self.set_permissions(user, domains)
         if aliases:
             for alias in aliases:
-                models.alias.modify_or_create_alias(
+                models.Alias.objects.modify_or_create(
                     address="{}@{}".format(alias["localpart"], alias["domain"]),
                     recipients=[user.username],
                     creator=creator,
@@ -577,7 +577,7 @@ class WritableAccountSerializer(v1_serializers.WritableAccountSerializer):
             alias_recipients = instance.mailbox.alias_addresses
             for alias in aliases:
                 address = "{}@{}".format(alias["localpart"], alias["domain"])
-                models.alias.modify_or_create_alias(
+                models.Alias.objects.modify_or_create(
                     address=address,
                     recipients=[validated_data["username"]],
                     creator=creator,
diff --git a/modoboa/admin/models/alias.py b/modoboa/admin/models/alias.py
index 6d3485435..d42eb95e4 100644
--- a/modoboa/admin/models/alias.py
+++ b/modoboa/admin/models/alias.py
@@ -70,7 +70,7 @@ class AliasManager(models.Manager):
             alias.set_recipients(recipients)
         return alias
 
-    def modify_or_create_alias(self, address, recipients, creator, domain):
+    def modify_or_create(self, address, recipients, creator, domain):
         """Add recipient if the alias already exists or create it."""
 
         alias = Alias.objects.filter(address=address, internal=False)
diff --git a/modoboa/core/commands/templates/urls.py.tpl b/modoboa/core/commands/templates/urls.py.tpl
index e3df451c4..143764d85 100644
--- a/modoboa/core/commands/templates/urls.py.tpl
+++ b/modoboa/core/commands/templates/urls.py.tpl
@@ -1,4 +1,4 @@
-from django.conf.urls import include, path
+from django.urls import include, path
 
 urlpatterns = [
     path(r'', include('modoboa.urls')),
diff --git a/modoboa/core/extensions.py b/modoboa/core/extensions.py
index 7d1103eac..0aab96f56 100644
--- a/modoboa/core/extensions.py
+++ b/modoboa/core/extensions.py
@@ -1,7 +1,7 @@
 """Extension management."""
 
 from django.conf import settings
-from django.conf.urls import include
+from django.urls import include
 from django.urls import re_path
 from django.utils.encoding import smart_str