diff --git a/beetsplug/mbsync.py b/beetsplug/mbsync.py
index bace44e5a..d82fd3cb7 100644
--- a/beetsplug/mbsync.py
+++ b/beetsplug/mbsync.py
@@ -20,6 +20,7 @@ from beets.plugins import BeetsPlugin
 from beets import autotag, library, ui, util
 from beets.autotag import hooks
 from beets import config
+from beets import dbcore
 
 log = logging.getLogger('beets')
 
@@ -49,7 +50,9 @@ def mbsync_singletons(lib, query, move, pretend, write):
     """Synchronize matching singleton items.
     """
     singletons_query = library.get_query(query, library.Item)
-    singletons_query.subqueries.append(library.BooleanQuery('singleton', True))
+    singletons_query.subqueries.append(
+        dbcore.query.BooleanQuery('singleton', True)
+    )
     for s in lib.items(singletons_query):
         if not s.mb_trackid:
             log.info(u'Skipping singleton {0}: has no mb_trackid'