diff --git a/modoboa/extensions/postfix_relay_domains/factories.py b/modoboa/extensions/postfix_relay_domains/factories.py
index 1a0c0a5a2..74400e0fb 100644
--- a/modoboa/extensions/postfix_relay_domains/factories.py
+++ b/modoboa/extensions/postfix_relay_domains/factories.py
@@ -4,14 +4,22 @@ from . import models
 
 
 class ServiceFactory(factory.DjangoModelFactory):
-    FACTORY_FOR = models.Service
-    FACTORY_DJANGO_GET_OR_CREATE = ('name', )
+
+    """Factory to create Service instances."""
+
+    class Meta:
+        model = models.Service
+        django_get_or_create = ('name', )
 
     name = 'dummy'
 
 
 class RelayDomainFactory(PermissionFactory):
-    FACTORY_FOR = models.RelayDomain
+
+    """Factory to create RelayDomain instances."""
+
+    class Meta:
+        model = models.RelayDomain
 
     target_host = 'external.host.tld'
     enabled = True
@@ -20,6 +28,10 @@ class RelayDomainFactory(PermissionFactory):
 
 
 class RelayDomainAliasFactory(PermissionFactory):
-    FACTORY_FOR = models.RelayDomainAlias
+
+    """Factory to create RelayDomainAliases instances."""
+
+    class Meta:
+        model = models.RelayDomainAlias
 
     enabled = True