diff --git a/doc/requirements.txt b/doc/requirements.txt
index b9c5e1f..711fb97 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,3 +1,4 @@
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
diff --git a/lower-constraints.txt b/lower-constraints.txt
index 9c81629..797dd07 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -90,6 +90,7 @@ rjsmin==1.0.12
 semantic-version==2.6.0
 simplejson==3.13.2
 six==1.11.0
+sphinx==1.6.2
 stevedore==1.28.0
 testrepository==0.0.20
 testtools==2.3.0