diff --git a/ldap-requirements.txt b/ldap-requirements.txt
index 212b582a2..35eaac975 100644
--- a/ldap-requirements.txt
+++ b/ldap-requirements.txt
@@ -1 +1 @@
-django-auth-ldap
+django-auth-ldap>=1.2.13
diff --git a/modoboa/lib/authbackends.py b/modoboa/lib/authbackends.py
index df9894f1e..995c24272 100644
--- a/modoboa/lib/authbackends.py
+++ b/modoboa/lib/authbackends.py
@@ -108,7 +108,7 @@ try:
         def authenticate(self, username, password):
             if self.global_params["authentication_type"] == "ldap":
                 return super(LDAPBackend, self).authenticate(
-                    username, password)
+                    username=username, password=password)
             return None
 
 except ImportError: