diff --git a/sqlalchemy_utils/functions/orm.py b/sqlalchemy_utils/functions/orm.py
index ef8ac7d..6008a1b 100644
--- a/sqlalchemy_utils/functions/orm.py
+++ b/sqlalchemy_utils/functions/orm.py
@@ -5,7 +5,6 @@ except ImportError:
 
 from functools import partial
 from inspect import isclass
-from itertools import chain
 from operator import attrgetter
 
 import six