diff --git a/test-requirements.txt b/test-requirements.txt
index f7c6fb4a8..275b2aaf3 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -9,7 +9,7 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=2.0.0 # BSD
 oslotest>=3.2.0 # Apache-2.0
 requests-mock>=1.1.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
 sphinxcontrib-httpdomain>=1.3.0 # BSD
 testtools>=2.2.0 # MIT
 sphinxcontrib-blockdiag>=1.5.4 # BSD