diff --git a/core/prelude-packages.el b/core/prelude-packages.el
index 676ca9b..800af9e 100644
--- a/core/prelude-packages.el
+++ b/core/prelude-packages.el
@@ -200,6 +200,10 @@ 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)))
 
+(when (package-installed-p 'adoc-mode)
+  (add-to-list 'auto-mode-alist '("\\.adoc\\'" 'adoc-mode))
+  (add-to-list 'auto-mode-alist '("\\.asciidoc\\'" 'adoc-mode)))
+
 (when (package-installed-p 'pkgbuild-mode)
   (add-to-list 'auto-mode-alist '("PKGBUILD\\'" . pkgbuild-mode)))