diff --git a/docs/conf.py.in b/docs/conf.py.in
index c5db6e684..e6925b044 100644
--- a/docs/conf.py.in
+++ b/docs/conf.py.in
@@ -63,4 +63,4 @@ html_static_path = ['static']
 
 
 def setup(app):
-    app.add_stylesheet('css/extra.css')  # may also be an URL
\ No newline at end of file
+    app.add_css_file('css/extra.css')  # may also be an URL