diff --git a/core/prelude-packages.el b/core/prelude-packages.el
index eddb179..9cb6fd1 100644
--- a/core/prelude-packages.el
+++ b/core/prelude-packages.el
@@ -201,10 +201,12 @@ PACKAGE is installed only if not already present.  The file is opened in MODE."
   (add-to-list 'auto-mode-alist '("\\.markdown\\'" . gfm-mode))
   (add-to-list 'auto-mode-alist '("\\.md\\'" . gfm-mode)))
 
+;; same with adoc-mode
 (when (package-installed-p 'adoc-mode)
-  (add-to-list 'auto-mode-alist '("\\.adoc\\'" 'adoc-mode))
-  (add-to-list 'auto-mode-alist '("\\.asciidoc\\'" 'adoc-mode)))
+  (add-to-list 'auto-mode-alist '("\\.adoc\\'" . adoc-mode))
+  (add-to-list 'auto-mode-alist '("\\.asciidoc\\'" . adoc-mode)))
 
+;; and pkgbuild-mode
 (when (package-installed-p 'pkgbuild-mode)
   (add-to-list 'auto-mode-alist '("PKGBUILD\\'" . pkgbuild-mode)))