diff --git a/docs/conf.py b/docs/conf.py
index 6ab5959d5..18b806846 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -31,6 +31,7 @@ extensions = [
     'sphinx.ext.autodoc',
     'sphinx.ext.coverage',
     'sphinx.ext.intersphinx',
+    'sphinx.ext.viewcode',
 ]
 
 # Add any paths that contain templates here, relative to this directory.