diff --git a/lisp/acdw.el b/lisp/acdw.el
index a673e4a..10a51c1 100644
--- a/lisp/acdw.el
+++ b/lisp/acdw.el
@@ -139,6 +139,10 @@ active, or else the entire buffer."
                   (= (line-beginning-position) (line-end-position)))
         (insert "\n")))))
 
+(defcustom +open-paragraph-ignore-modes '(special-mode lui-mode comint-mode)
+  "Modes in which `+open-paragraph' makes no sense."
+  :type '(repeat function))
+
 (defun +open-paragraph (&optional arg)
   "Open a paragraph after paragraph at point.
 A paragraph is defined as continguous non-empty lines of text
@@ -149,7 +153,7 @@ Called with prefix ARG, open a paragraph before point."
   ;; TODO: Take an integer as ARG, allowing for skipping paragraphs up and down.
   (interactive "*P")
   ;; TODO: add `+open-paragraph-ignore-modes'
-  (unless (derived-mode-p 'special-mode 'lui-mode 'comint-mode)
+  (unless (apply #'derived-mode-p +open-paragraph-ignore-modes)
     ;; Go to next blank line.  This /isn't/ `end-of-paragraph-text' because
     ;; that's weird with org, and I'm guessing other modes too.
     (unless (looking-at "^$") (forward-line (if arg -1 +1)))