diff --git a/test-requirements.txt b/test-requirements.txt
index 02b1a2815..2e9859a28 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -11,7 +11,7 @@ Babel!=2.4.0,>=2.3.4 # BSD
 openstackdocstheme>=1.17.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 testtools>=2.2.0 # MIT
 tempest>=17.1.0 # Apache-2.0
 os-testr>=1.0.0 # Apache-2.0