diff --git a/django_mongodb_engine/base.py b/django_mongodb_engine/base.py
index 12ddd2e1..ec71d112 100644
--- a/django_mongodb_engine/base.py
+++ b/django_mongodb_engine/base.py
@@ -272,7 +272,7 @@ def pop(name, default=None):
             raise ImproperlyConfigured, exc_info[1], exc_info[2]
 
         if user and password:
-            if not self.database.authenticate(user, password):
+            if not self.database.authenticate(user, password, source=options.get('authsource')):
                 raise ImproperlyConfigured("Invalid username or password.")
 
         self.connected = True
diff --git a/docs/source/reference/settings.rst b/docs/source/reference/settings.rst
index e0ff5458..1d8053ac 100644
--- a/docs/source/reference/settings.rst
+++ b/docs/source/reference/settings.rst
@@ -14,7 +14,10 @@ Additional flags may be passed to :class:`pymongo.MongoClient` using the
            'NAME' : 'my_database',
            ...
            'OPTIONS' : {
-               'socketTimeoutMS' : 500,
+               'slave_okay' : True,
+               'tz_aware' : True,
+               'network_timeout' : 42,
+               'authSource': 'authentication_database_name'
                ...
            }
        }