diff --git a/planetstack/observer/steps/garbage_collector.py b/planetstack/observer/steps/garbage_collector.py
index 9e2a37d..431623d 100644
--- a/planetstack/observer/steps/garbage_collector.py
+++ b/planetstack/observer/steps/garbage_collector.py
@@ -1,5 +1,6 @@
 import os
 import base64
+from django.db.models import F, Q
 from planetstack.config import Config
 from observer.openstacksyncstep import OpenStackSyncStep