diff --git a/test-requirements.txt b/test-requirements.txt
index ca5c8fa..02b5866 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -15,7 +15,7 @@ stestr>=2.0.0 # Apache-2.0
 
 # Docs Requirements
 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
 oslosphinx>=4.7.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 docutils>=0.11 # OSI-Approved Open Source, Public Domain