diff --git a/lib/ansible/modules/extras/database/misc/mongodb_user.py b/lib/ansible/modules/extras/database/misc/mongodb_user.py
index 266b902fda7..e0d1342bc41 100644
--- a/lib/ansible/modules/extras/database/misc/mongodb_user.py
+++ b/lib/ansible/modules/extras/database/misc/mongodb_user.py
@@ -315,7 +315,7 @@ def main():
     ssl_cert_reqs = None
     if ssl:
         ssl_cert_reqs = getattr(ssl_lib, module.params['ssl_cert_reqs'])
-    roles = module.params['roles']
+    roles = module.params['roles'] or []
     state = module.params['state']
     update_password = module.params['update_password']