diff --git a/requirements.txt b/requirements.txt
index 6b5875ab..b220839c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -22,7 +22,7 @@ psycopg2
 python-designateclient>=1.0.0
 python-glanceclient>=0.15.0
 python-keystoneclient>=1.1.0
-python-novaclient>=2.18.0
+python-novaclient>=2.18.0,!=2.21.0
 python-neutronclient>=2.3.6,<3
 python-cinderclient>=1.1.0
 python-heatclient>=0.3.0