diff --git a/test-requirements.txt b/test-requirements.txt
index 3f66343..a55fbaa 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -10,7 +10,7 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 
 # These are needed for docs generation
 openstackdocstheme>=1.17.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 reno>=2.5.0 # Apache-2.0
 
 eventlet!=0.18.3,!=0.20.1,<0.21.0,>=0.18.2 # MIT