diff --git a/requirements.txt b/requirements.txt
index 9b2e1e8..4016b7c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 openstackdocstheme>=1.11.0  # Apache-2.0
-sphinx>=1.6.2 # BSD
-
+sphinx!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7'  # BSD
+sphinx!=1.6.6,!=1.6.7;python_version>='3.4'  # BSD
 six>=1.9.0
 sphinxcontrib-httpdomain
 sphinx_rtd_theme