diff --git a/requirements.txt b/requirements.txt
index 3a1f2f3..d9c89bf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,5 +4,6 @@
 
 dnspython>=1.16.0  # http://www.dnspython.org/LICENSE
 ddt>=1.0.1 # MIT
+oslo.serialization>=2.25.0 # Apache-2.0
 testtools>=2.2.0 # MIT
 tempest>=17.1.0 # Apache-2.0