diff --git a/doc/conf.py b/doc/conf.py
index 84ea8de0f2d..b630823e5fa 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -25,7 +25,7 @@
 templates_path = ['_templates']
 source_suffix = '.rst'
 source_encoding = 'utf-8-sig'
-master_doc = 'index'
+root_doc = 'index'
 
 # extlinks -- see http://www.sphinx-doc.org/en/stable/ext/extlinks.html
 extlinks = {