diff --git a/docs/source/conf.py b/docs/source/conf.py
index ce2bb388069..1cdba5b1ec8 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -52,10 +52,7 @@
 # The suffix(es) of source filenames.
 # You can specify multiple suffix as a list of string:
 #
-source_suffix = {
-    '.rst': 'restructuredtext',
-    '.md': 'markdown',
-}
+source_suffix = ['.rst', '.md']
 autosectionlabel_prefix_document = True
 
 # The master toctree document.