diff --git a/test-requirements.txt b/test-requirements.txt
index 9003c6cd..52801b03 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -20,6 +20,6 @@ os-testr>=1.0.0 # Apache-2.0
 bandit>=1.1.0 # Apache-2.0
 
 # 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
 reno>=2.5.0 # Apache-2.0