diff --git a/modules/languages/siren-conf.el b/modules/languages/siren-conf.el
index f7a380b..17ecdad 100644
--- a/modules/languages/siren-conf.el
+++ b/modules/languages/siren-conf.el
@@ -9,6 +9,7 @@
 (require 'siren-prog-mode)
 
 (use-package conf-mode
+  :straight (:type built-in)
   :mode
   "/Procfile\\'"
   "/\\.env\\'"