diff --git a/lld/docs/conf.py b/lld/docs/conf.py
index 7d4fc0c5ad75f..ee93c01f7f324 100644
--- a/lld/docs/conf.py
+++ b/lld/docs/conf.py
@@ -134,7 +134,7 @@
 #html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-html_sidebars = {'index': 'indexsidebar.html'}
+html_sidebars = {'index': ['indexsidebar.html']}
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.