diff --git a/composer/workflows/airflow_db_cleanup.py b/composer/workflows/airflow_db_cleanup.py
index 4eee89ef9ab..0065541e467 100644
--- a/composer/workflows/airflow_db_cleanup.py
+++ b/composer/workflows/airflow_db_cleanup.py
@@ -459,7 +459,7 @@ def cleanup_function(**context):
             dags = session.query(airflow_db_model.dag_id).distinct()
             session.commit()
 
-            list_dags = [str(list(dag)[0]) for dag in dags] + [None]
+            list_dags = [str(list(dag)[0]) for dag in dags]
             for dag_id in list_dags:
                 query = build_query(
                     session=session,