diff --git a/users/migrations/0067_serveurpermission.py b/users/migrations/0067_serveurpermission.py
index de4c3976..a5ea8387 100644
--- a/users/migrations/0067_serveurpermission.py
+++ b/users/migrations/0067_serveurpermission.py
@@ -23,7 +23,7 @@ class Migration(migrations.Migration):
             perm = permissions.objects.using(db_alias).create(
             codename='serveur',
             name='Serveur',
-            content_type=contenttype.objects.using(db_alias).filter(model='machine').first() 
+            content_type=contenttype.objects.get_for_model(machine)
             )
         group_object = rights.objects.using(db_alias).filter(unix_name='serveur').first()
         if not group_object:
diff --git a/users/migrations/0068_auto_20180107_2245.py b/users/migrations/0068_auto_20180107_2245.py
index 3ce232dc..27c4f446 100644
--- a/users/migrations/0068_auto_20180107_2245.py
+++ b/users/migrations/0068_auto_20180107_2245.py
@@ -17,8 +17,9 @@ class Migration(migrations.Migration):
         rights = apps.get_model("users", "ListRight")
         for right in critical_rights:
             rg = rights.objects.using(db_alias).filter(unix_name=right).first()
-            rg.critical=True
-            rg.save()
+            if rg:
+                rg.critical=True
+                rg.save()
 
     def untransfer_permissions(apps, schema_editor):
         return