diff --git a/requirements.txt b/requirements.txt
index c411569aa..bc109a01d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@
 
 pbr>=1.6 # Apache-2.0
 
-iso8601>=0.1.9 # MIT
+iso8601>=0.1.11 # MIT
 debtcollector>=1.2.0 # Apache-2.0
 keystoneauth1>=2.1.0 # Apache-2.0
 oslo.config>=3.9.0 # Apache-2.0