diff --git a/doc/_themes/sphinx13/theme.conf b/doc/_themes/sphinx13/theme.conf
index 876b19803fb..19a480a6b36 100644
--- a/doc/_themes/sphinx13/theme.conf
+++ b/doc/_themes/sphinx13/theme.conf
@@ -1,4 +1,4 @@
 [theme]
 inherit = basic
 stylesheet = sphinx13.css
-pygments_style = trac
+pygments_style = default