diff --git a/oml/library.py b/oml/library.py
index d70df0c..7f7f2b6 100644
--- a/oml/library.py
+++ b/oml/library.py
@@ -245,8 +245,9 @@ class Peer(object):
             state.db.session.commit()
         if state.shutdown:
             return
-        for itemid in getpreview:
-            state.tasks.queue('getpreview', itemid)
+        if state.tasks:
+            for itemid in getpreview:
+                state.tasks.queue('getpreview', itemid)
         update_items = remove + add
 
         current_lists = set(l.name for l in u.lists.all() if l.name)