diff --git a/docs/source/conf.py b/docs/source/conf.py
index a91496548940056277bfe40ebf55b15c3f763afa..4fd8aa997a65011a263256b9f19392025878e2df 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -137,7 +137,7 @@
 
 # Custom sidebar templates, maps document names to template names.
 html_sidebars = {
-    'index': 'indexsidebar.html'
+    'index': ['indexsidebar.html'],
 }
 
 # Additional templates that should be rendered to pages, maps page names to