diff --git a/mongoengine/connection.py b/mongoengine/connection.py
index 3c53ea3c..abab269f 100644
--- a/mongoengine/connection.py
+++ b/mongoengine/connection.py
@@ -137,11 +137,12 @@ def get_db(alias=DEFAULT_CONNECTION_NAME, reconnect=False):
     if alias not in _dbs:
         conn = get_connection(alias)
         conn_settings = _connection_settings[alias]
-        _dbs[alias] = conn[conn_settings['name']]
+        db = conn[conn_settings['name']]
         # Authenticate if necessary
         if conn_settings['username'] and conn_settings['password']:
-            _dbs[alias].authenticate(conn_settings['username'],
-                                     conn_settings['password'])
+            db.authenticate(conn_settings['username'],
+                            conn_settings['password'])
+        _dbs[alias] = db
     return _dbs[alias]