diff --git a/test-requirements.txt b/test-requirements.txt
index 51c2f26e..cd893fc9 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -9,7 +9,7 @@ requests>=2.14.2 # Apache-2.0
 ndg-httpsclient>=0.4.2;python_version<'3.0' # BSD
 
 # this is required for the docs build jobs
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 openstackdocstheme>=1.17.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0