diff --git a/doc/conf.py b/doc/conf.py
index 0d661ba3ee..38f4c1261b 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -116,7 +116,7 @@
     html_theme = 'sphinx_rtd_theme'
 
 def setup(app):
-    app.add_stylesheet('fix_rtd.css')
+    app.add_css_file('fix_rtd.css')
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the