diff --git a/doc/source/conf.py b/doc/source/conf.py
index 13f075b29..3a0ef1551 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -477,6 +477,6 @@ def update_context(app, pagename, templatename, context, doctree):
 
 def setup(app):
     app.connect('html-page-context', update_context)
-    app.add_stylesheet('css/custom.css')
+    app.add_css_file('css/custom.css')
     # Custom directives
     app.add_directive('customgalleryitem', CustomGalleryItemDirective)