diff --git a/doc/source/conf.py b/doc/source/conf.py
index 7541693..1ed9b06 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -60,7 +60,7 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'sphinx_rtd_theme'
+html_theme = "sphinx_book_theme"
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,