diff --git a/mysite/_config/config.yml b/mysite/_config/config.yml
index 17910fc..3beba7e 100644
--- a/mysite/_config/config.yml
+++ b/mysite/_config/config.yml
@@ -8,6 +8,8 @@ After:
 # See http://doc.silverstripe.org/framework/en/topics/configuration
 # Caution: Indentation through two spaces, not tabs
 SSViewer:
-  theme: 'simple'
+  themes:
+    - 'simple'
+    - '$default'
 Debug:
   friendly_error_httpcode: true