diff --git a/modules/prelude-ruby.el b/modules/prelude-ruby.el
index ade7d94..5a3df41 100644
--- a/modules/prelude-ruby.el
+++ b/modules/prelude-ruby.el
@@ -44,6 +44,7 @@
 (add-to-list 'auto-mode-alist '("Gemfile\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("Guardfile\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("Capfile\\'" . ruby-mode))
+(add-to-list 'auto-mode-alist '("\\.cap\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("\\.thor\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("\\.rabl\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("Thorfile\\'" . ruby-mode))