diff --git a/doc/requirements.txt b/doc/requirements.txt
index d204a868f..b4b677a25 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 openstackdocstheme>=1.20.0 # Apache-2.0
 sphinx>=1.6.5,!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7' # BSD
-sphinx>=1.6.5,!=1.6.6,!=1.6.7;python_version>='3.4' # BSD
+sphinx>=1.6.5,!=1.6.6,!=1.6.7,!=2.1.0;python_version>='3.4' # BSD
 sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
 reno>=2.7.0 # Apache-2.0
 sphinxcontrib-apidoc>=0.2.0  # BSD