diff --git a/README.rst b/README.rst
index f51d8b2e9..c725347ef 100644
--- a/README.rst
+++ b/README.rst
@@ -34,10 +34,15 @@ This theme is distributed on PyPI_ and can be installed with ``pip``:
    $ pip install sphinx-rtd-theme
 
 To use the theme in your Sphinx project, you will need to edit
-your ``conf.py`` file's ``html_theme`` setting:
+your ``conf.py`` file's ``extensions`` and ``html_theme`` settings:
 
 .. code:: python
 
+    extensions = [
+        ...
+        "sphinx_rtd_theme",
+    ]
+
     html_theme = "sphinx_rtd_theme"
 
 .. admonition:: See also: