diff --git a/test-requirements.txt b/test-requirements.txt
index fee525a..e9399f4 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -10,7 +10,7 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 coverage!=4.4,>=4.0 # 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
 oslo.config>=5.1.0 # Apache-2.0