diff --git a/test-requirements.txt b/test-requirements.txt
index d3a1735b..ba5ab723 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -7,7 +7,7 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 oslotest>=3.2.0 # Apache-2.0
 python-openstackclient>=3.12.0 # 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
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT