diff --git a/machines/migrations/0107_fix_lowercase_domain.py b/machines/migrations/0107_fix_lowercase_domain.py
new file mode 100644
index 00000000..e47a4680
--- /dev/null
+++ b/machines/migrations/0107_fix_lowercase_domain.py
@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+from django.core.exceptions import ValidationError
+import logging
+
+def fix_duplicate(apps, schema_editor):
+    logger = logging.getLogger(__name__)
+    db_alias = schema_editor.connection.alias
+    Domain = apps.get_model("machines", "Domain")
+    domains_to_fix = filter(lambda m : not m.name.islower(), Domain.objects.using(db_alias).all())
+    for domain in domains_to_fix:
+        try:
+            domain.name = domain.name.lower()
+            domain.validate_unique()
+            domain.clean()
+        except ValidationError:
+            old_name = domain.name
+            domain.name = domain.name.lower() + str(domain.interface_parent.id)
+            domain.clean()
+            warning_message = "Warning : Domain %s has been renamed %s due to dns uniqueness" % (old_name, domain.name)
+            logger.warning(warning_message)
+        domain.save()
+
+def unfix_duplicate(apps, schema_editor):
+    return
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("machines", "0106_auto_20191120_0159")]
+
+    operations = [
+        migrations.RunPython(fix_duplicate, unfix_duplicate),
+    ]
diff --git a/machines/models.py b/machines/models.py
index 96a6eb48..55fb8838 100644
--- a/machines/models.py
+++ b/machines/models.py
@@ -1623,15 +1623,15 @@ class Domain(RevMixin, AclMixin, FieldPermissionModelMixin, models.Model):
             raise ValidationError(
                 _("You can't create a CNAME record pointing to itself.")
             )
-        HOSTNAME_LABEL_PATTERN = re.compile(r"(?!-)[A-Z\d-]+(?<!-)$", re.IGNORECASE)
-        dns = self.name.lower()
-        if len(dns) > 63:
+        HOSTNAME_LABEL_PATTERN = re.compile(r"(?!-)[a-z\d-]+(?<!-)$")
+        self.name = self.name.lower()
+        if len(self.name) > 63:
             raise ValidationError(
-                _("The domain name %s is too long (over 63 characters).") % dns
+                _("The domain name %s is too long (over 63 characters).") % self.name
             )
-        if not HOSTNAME_LABEL_PATTERN.match(dns):
+        if not HOSTNAME_LABEL_PATTERN.match(self.name):
             raise ValidationError(
-                _("The domain name %s contains forbidden characters.") % dns
+                _("The domain name %s contains forbidden characters.") % self.name
             )
         self.validate_unique()
         super(Domain, self).clean()