diff --git a/lower-constraints.txt b/lower-constraints.txt
index 7cb89b053b..536e8b61ed 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -85,6 +85,7 @@ stestr==2.0.0
 stevedore==1.28.0
 testtools==2.3.0
 traceback2==1.4.0
+unittest2==1.1.0
 urllib3==1.22
 voluptuous==0.11.1
 wrapt==1.10.11