diff --git a/mode-customizations/ruby-mode.el b/mode-customizations/ruby-mode.el
index 766592c..54b90e3 100644
--- a/mode-customizations/ruby-mode.el
+++ b/mode-customizations/ruby-mode.el
@@ -5,6 +5,7 @@
 (add-to-list 'auto-mode-alist '("\\.rake\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("\\.gemspec\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("\\.rabl\\'" . ruby-mode))
+(add-to-list 'auto-mode-alist '("\\.jbuilder\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("\\.prawn\\'" . ruby-mode))
 (add-to-list 'auto-mode-alist '("Capfile" . ruby-mode))
 (add-to-list 'auto-mode-alist '("Gemfile" . ruby-mode))