diff --git a/docs/conf.py b/docs/conf.py
index cd9a4e78a53165d0d2eb81b5fd0677d2e111d255..a769db90c9b3d4cd506a0abb4bb290e5d6c04c57 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -48,7 +48,7 @@ templates_path = ['_templates']
 # You can specify multiple suffix as a list of string:
 #
 # source_suffix = ['.rst', '.md']
-source_suffix = '.rst'
+source_suffix = {'.rst': 'restructuredtext'}
 
 # The master toctree document.
 master_doc = 'index'