diff --git a/test-requirements.txt b/test-requirements.txt
index 0e985722..6e92972e 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -6,7 +6,7 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 mock>=2.0.0 # BSD
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 openstackdocstheme>=1.17.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 six>=1.10.0 # MIT