diff --git a/modoboa/lib/form_utils.py b/modoboa/lib/form_utils.py
index e1c85a416..31b6dc421 100644
--- a/modoboa/lib/form_utils.py
+++ b/modoboa/lib/form_utils.py
@@ -13,6 +13,7 @@ from django.forms.fields import Field
 from django.forms.widgets import RadioSelect
 from django.forms.widgets import RadioChoiceInput
 from django.shortcuts import render
+from django.utils import six
 from django.utils.encoding import force_text
 from django.utils.html import conditional_escape
 from django.utils.safestring import mark_safe
@@ -21,7 +22,11 @@ from django.utils.translation import ugettext as _, ugettext_lazy
 from modoboa.lib.exceptions import BadRequest
 from modoboa.lib.web_utils import render_to_json_response
 
-ABC = abc.ABCMeta(b"ABC", (object,), {})  # compatible with Python 2 *and* 3
+if six.PY2:
+    meta_name = b"ABC"
+else:
+    meta_name = "ABC"
+ABC = abc.ABCMeta(meta_name, (object,), {})  # compatible with Python 2 *and* 3
 
 
 class WizardStep(object):