diff --git a/test-requirements.txt b/test-requirements.txt
index a2a8c7e..6641007 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -7,7 +7,7 @@ oslotest>=3.2.0 # Apache-2.0
 
 # 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
 
 # for testing optional parts
 oslo.config>=5.1.0 # Apache-2.0