diff --git a/doc/requirements.txt b/doc/requirements.txt
index 7b1977e5..0785be45 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,4 +1,5 @@
-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
 sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
 sphinxcontrib-httpdomain>=1.3.0 # BSD