diff --git a/docs/source/conf.py b/docs/source/conf.py
index 451a134561..6f82deda28 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -50,6 +50,7 @@
     "sphinx.ext.intersphinx",
     "sphinx.ext.autosectionlabel",
     "sphinx_copybutton",
+    "sphinx_rtd_theme",
 ]
 
 # Add any paths that contain templates here, relative to this directory.