diff --git a/airflow/migrations/versions/0045_b3b105409875_add_root_dag_id_to_dag.py b/airflow/migrations/versions/0045_b3b105409875_add_root_dag_id_to_dag.py
index 3d184e6b9bd1d..f879450369ab8 100644
--- a/airflow/migrations/versions/0045_b3b105409875_add_root_dag_id_to_dag.py
+++ b/airflow/migrations/versions/0045_b3b105409875_add_root_dag_id_to_dag.py
@@ -27,6 +27,8 @@
 import sqlalchemy as sa
 from alembic import op
 
+from airflow.migrations.db_types import StringID
+
 # revision identifiers, used by Alembic.
 revision = 'b3b105409875'
 down_revision = 'd38e04c12aa2'
@@ -37,7 +39,7 @@
 
 def upgrade():
     """Apply Add ``root_dag_id`` to ``DAG``"""
-    op.add_column('dag', sa.Column('root_dag_id', sa.String(length=250), nullable=True))
+    op.add_column('dag', sa.Column('root_dag_id', StringID(), nullable=True))
     op.create_index('idx_root_dag_id', 'dag', ['root_dag_id'], unique=False)