diff --git a/test-requirements.txt b/test-requirements.txt
index 775eaec22..e98669ef8 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -15,7 +15,7 @@ python-openstackclient>=3.12.0 # Apache-2.0
 python-subunit>=1.0.0 # Apache-2.0/BSD
 reno>=2.5.0 # Apache-2.0
 requests-mock>=1.1.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
 testscenarios>=0.4 # Apache-2.0/BSD