diff --git a/test-requirements.txt b/test-requirements.txt
index fc8ab1b..02564e2 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -8,7 +8,7 @@ flake8-import-order>=0.13 # LGPLv3
 # documentation
 doc8>=0.6.0 # Apache-2.0
 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
 openstackdocstheme>=1.20.0 # Apache-2.0
 # releasenotes
 reno>=2.5.0 # Apache-2.0