diff --git a/requirements.txt b/requirements.txt
index ffcc1771a2..aa4163e046 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ django_openstack_auth>=1.1.3
 eventlet>=0.13.0
 kombu>=2.4.8
 lesscpy>=0.9j
-iso8601>=0.1.4,!=0.1.5,!=0.1.6
+iso8601>=0.1.8
 netaddr>=0.7.6
 python-cinderclient>=1.0.6
 python-glanceclient>=0.9.0