diff --git a/compose.override.yml b/compose.override.yml
index 5195245..071f70e 100644
--- a/compose.override.yml
+++ b/compose.override.yml
@@ -6,10 +6,8 @@ services:
       - POSTGRES_DB=${POSTGRES_DB}
       - POSTGRES_USER=${POSTGRES_USER}
       - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
-        
       - JUPYTERHUB_CRYPT_KEY=${JUPYTERHUB_CRYPT_KEY}
       - DOCKER_NETWORK_NAME=${DOCKER_NETWORK_NAME}
-      - NBGRADER_DB_URL=postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@postgres:5432/${NBGRADER_DB}
     ports:
       - ${JUPYTERHUB_PORT:-8000}:8000
     volumes: