diff --git a/beets/dbcore/db.py b/beets/dbcore/db.py
index 54fb10f47..cbdaf5a7f 100644
--- a/beets/dbcore/db.py
+++ b/beets/dbcore/db.py
@@ -301,6 +301,7 @@ class Model(object):
         """
         self._check_db()
         stored_obj = self._db._get(type(self), self.id)
+        assert stored_obj is not None, "object {0} not in DB".format(self.id)
         self.update(dict(stored_obj))
         self.clear_dirty()