diff --git a/doc/requirements.txt b/doc/requirements.txt
index a4fd173..a78d386 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -10,7 +10,8 @@
 # automatically be proposed to all the repositories which use it.
 
 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
+sphinx>=1.8.0,!=2.1.0,>=1.6.2;python_version>='3.4'  # BSD
+sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0