diff --git a/test-requirements.txt b/test-requirements.txt
index be25cb7b..9a7e07c2 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -13,6 +13,6 @@ pycodestyle>=2.5.0 # MIT
 
 # release notes
 sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
 reno>=2.5.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0