diff --git a/test-requirements.txt b/test-requirements.txt
index bc5980ed9..510edb3e9 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -6,7 +6,7 @@ doc8>=0.6.0 # Apache-2.0
 flake8-import-order>=0.13 # LGPLv3
 hacking>=1.0.0 # Apache-2.0
 mock>=2.0.0 # BSD
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 openstackdocstheme>=1.17.0 # Apache-2.0
 os-testr>=1.0.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0