diff --git a/doc/source/conf.py b/doc/source/conf.py
index 6cbf48a2..0cef1f7c 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -38,6 +38,7 @@ sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__),
 # extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['sphinx.ext.autodoc',
+              'sphinx.ext.todo',
               'sphinx.ext.coverage',
               'sphinx.ext.intersphinx',
               'openstackdocstheme',