diff --git a/requirements.txt b/requirements.txt
index f6d9b4f..90858ca 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,3 +9,4 @@ oslo.i18n>=1.5.0 # Apache-2.0
 oslo.serialization>=1.4.0 # Apache-2.0
 oslo.utils>=2.0.0 # Apache-2.0
 keystoneauth1>=1.0.0
+six