diff --git a/test-requirements.txt b/test-requirements.txt
index 27bfe5be4..1b4ce3113 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -12,7 +12,7 @@ flake8-import-order>=0.13 # LGPLv3
 
 # Doc requirements
 doc8>=0.6.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
 openstackdocstheme>=1.17.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0