diff --git a/requirements.txt b/requirements.txt
index 1f8e59efa..709fa2e15 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -10,7 +10,7 @@ osc-lib>=1.0.2 # 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
 keystoneauth1>=2.10.0 # Apache-2.0
 requests>=2.10.0 # Apache-2.0
 simplejson>=2.2.0 # MIT