diff --git a/docs/conf.py b/docs/conf.py
index 40eb062..6b45309 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -28,7 +28,7 @@ import hy
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = []
+extensions = ['sphinx.ext.todo']
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']