advising-functions

You could define your own elisp function which modified the regexp and then passed it back to emacs. In pseudo-elisp: (defun my-query-replace-regexp (regexp) ; modify regexp to replace ( with \(, { with \{, etc. (query-replace-regexp modified-regexp) ) ; rebind C-% to use new regexp function (global-set-key “\C-%” ‘my-query-replace-regexp)