diff --git a/docs/conf.py b/docs/conf.py
index 16412089..1f8bb8fb 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -41,6 +41,7 @@
 extensions = [
 # To make ours look like readthedocs.io, change theme to "sphinx_rtd_theme",
 # pip install sphinx_rtd_theme, and uncomment extensions:
+    "sphinx_rtd_theme",
 #    "sphinx.ext.intersphinx",
 #    "sphinx.ext.autodoc",
 #    "sphinx.ext.mathjax",