diff --git a/requirements.txt b/requirements.txt
index 5cac45fe..86d9e35c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,7 +11,7 @@ requests>=2.10.0 # Apache-2.0
 oslo.i18n>=2.1.0 # Apache-2.0
 oslo.serialization>=1.10.0 # Apache-2.0
 oslo.utils>=3.16.0 # 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
 PrettyTable<0.8,>=0.7 # BSD
 cryptography!=1.3.0,>=1.0 # BSD/Apache-2.0
 decorator>=3.4.0 # BSD