diff --git a/test-requirements.txt b/test-requirements.txt
index 2cac5d9..69e0a9e 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -13,6 +13,7 @@ testtools>=2.2.0 # MIT
 
 # documentation
 doc8>=0.6.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.5 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.5,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.5;python_version>='3.4' # BSD
 reno>=2.5.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0