diff --git a/docs/conf.py b/docs/conf.py
index 2851bb1..f8799ab 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -76,9 +76,6 @@
 #
 html_theme = "sphinx_rtd_theme"
 
-# Use old HTML4 writer because sphinx_rtd_theme doesn't support new one yet
-html4_writer = True
-
 # 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,
 # so a file named "default.css" will overwrite the builtin "default.css".