diff --git a/machines/models.py b/machines/models.py
index 9eb6323a..fe1923bb 100644
--- a/machines/models.py
+++ b/machines/models.py
@@ -541,8 +541,7 @@ class Extension(RevMixin, AclMixin, models.Model):
     )
     soa = models.ForeignKey(
         'SOA',
-        on_delete=models.CASCADE,
-        default=SOA.new_default_soa
+        on_delete=models.CASCADE
     )
 
     class Meta:
diff --git a/re2o/mixins.py b/re2o/mixins.py
index c13e841c..2ee049cc 100644
--- a/re2o/mixins.py
+++ b/re2o/mixins.py
@@ -24,6 +24,7 @@ A set of mixins used all over the project to avoid duplicating code
 """
 
 from reversion import revisions as reversion
+from django.db import transaction
 
 
 class RevMixin(object):
@@ -33,13 +34,16 @@ class RevMixin(object):
     def save(self, *args, **kwargs):
         """ Creates a version of this object and save it to database """
         if self.pk is None:
-            reversion.set_comment("Création")
+            with transaction.atomic(), reversion.create_revision():
+                reversion.set_comment("Création")
+                return super(RevMixin, self).save(*args, **kwargs)
         return super(RevMixin, self).save(*args, **kwargs)
 
     def delete(self, *args, **kwargs):
         """ Creates a version of this object and delete it from database """
-        reversion.set_comment("Suppresion")
-        return super(RevMixin, self).delete(*args, **kwargs)
+        with transaction.atomic(), reversion.create_revision():
+            reversion.set_comment("Suppresion")
+            return super(RevMixin, self).delete(*args, **kwargs)
 
 
 class FormRevMixin(object):