diff --git a/config.org b/config.org
index a441cca..67c55ae 100644
--- a/config.org
+++ b/config.org
@@ -449,6 +449,14 @@ needs to be set up to install them if they aren't already.
       (add-hook 'js2-mode-hook 'prettier-js-mode)
     #+end_src
 
+** Prolog
+   =prolog-mode= comes with Emacs, but .pl files are assumed to be
+   Perl (which I never use, it scares me), so we need to change that.
+
+   #+begin_src emacs-lisp
+     (add-to-list 'auto-mode-alist '("\\.pl\\'" . prolog-mode))
+   #+end_src
+
 * Desktop
 ** EXWM
    One must fulfil the meme of doing everything with Emacs... still