diff --git a/doc/sphinx/conf.py b/doc/sphinx/conf.py
index e890933854..016ea8ed73 100644
--- a/doc/sphinx/conf.py
+++ b/doc/sphinx/conf.py
@@ -238,6 +238,6 @@ def run_generate_docs(_):
 
 # custom setup hook
 def setup(app):
-    app.add_stylesheet('kea.css')
+    app.add_css_file('kea.css')
 
     app.connect('builder-inited', run_generate_docs)