diff --git a/djangocms_installer/config/__init__.py b/djangocms_installer/config/__init__.py
index 82fb177..57e8979 100644
--- a/djangocms_installer/config/__init__.py
+++ b/djangocms_installer/config/__init__.py
@@ -36,7 +36,8 @@ def parse(args):
                         choices=('yes', 'no'),
                         default='yes', help='Activate CMS permission management')
     parser.add_argument('--languages', '-l', dest='languages', action='append',
-                        help='Languages to enable. Option can be provided multiple times, or as a comma separated list')
+                        help='Languages to enable. Option can be provided multiple times, or as a comma separated list. '
+                        'Only language codes supported by Django can be used here')
     parser.add_argument('--django-version', dest='django_version', action='store',
                         choices=('1.4', '1.5', '1.6', 'stable'),
                         default='stable', help='Django version')
diff --git a/docs/reference.rst b/docs/reference.rst
index 2789fb4..50f5cad 100644
--- a/docs/reference.rst
+++ b/docs/reference.rst
@@ -24,7 +24,9 @@ The following arguments can be overridden in :ref:`wizard_mode`
 * ``--timezone``, ``-t``: Optional default time zone, default: ``America/Chicago``
 * ``--reversion``, ``-e``: Install and configure reversion support, choices: ``yes|no``, default: ``yes``
 * ``--permissions``: Activate CMS permission management; choices: ``yes|no``, default: ``yes``
-* ``--languages``, ``-l``: Languages to enable. Option can be provided multiple times, or as a comma separated list
+* ``--languages``, ``-l``: Languages available for the project. Option can be provided multiple times, or as a
+  comma separated list.
+  Only language codes supported by Django can be used here. Refer to `django source`_ for a list of supported codes.
 * ``--django-version``: Django version;  choices: ``1.4|1.5|1.6|stable``, default: ``stable``
 * ``--cms-version``, ``-v``: django CMS version, choices: ``2.4|3.0|stable|develop``. default: ``stable``
 * ``--bootstrap``: Use Twitter Bootstrap as theme, choices: ``yes|no``, default: ``no``
@@ -62,3 +64,4 @@ advanced usage:
 
 
 .. _dj-database-url: https://github.com/kennethreitz/dj-database-url
+.. _django source: https://github.com/django/django/blob/master/django/conf/global_settings.py#L50
\ No newline at end of file