diff --git a/redbot/core/drivers/red_mongo.py b/redbot/core/drivers/red_mongo.py
index c4ae8ab87..61593ffe3 100644
--- a/redbot/core/drivers/red_mongo.py
+++ b/redbot/core/drivers/red_mongo.py
@@ -14,10 +14,15 @@ def _initialize(**kwargs):
     admin_pass = kwargs['PASSWORD']
     db_name = kwargs.get('DB_NAME', 'default_db')
 
-    url = "mongodb://{}:{}@{}:{}/{}".format(
-        admin_user, admin_pass, host, port,
-        db_name
-    )
+    if admin_user is not None and admin_pass is not None:
+        url = "mongodb://{}:{}@{}:{}/{}".format(
+            admin_user, admin_pass, host, port,
+            db_name
+        )
+    else:
+        url = "mongodb://{}:{}/{}".format(
+            host, port, db_name
+        )
 
     global _conn
     _conn = motor.motor_asyncio.AsyncIOMotorClient(url)