diff --git a/test-requirements.txt b/test-requirements.txt
index ff7b198123..0ff0e2268f 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -13,7 +13,7 @@ requests>=2.10.0 # Apache-2.0
 requests-mock>=1.0 # Apache-2.0
 sphinx!=1.3b1,<1.3,>=1.2.1 # BSD
 stevedore>=1.16.0 # Apache-2.0
-os-client-config!=1.19.0,!=1.19.1,!=1.20.0,!=1.20.1,>=1.13.1 # Apache-2.0
+os-client-config!=1.19.0,!=1.19.1,!=1.20.0,!=1.20.1,!=1.21.0,>=1.13.1 # Apache-2.0
 os-testr>=0.7.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT