Colin Rafferty <colin(a)xemacs.org&gt; writes: You'd have to be more tricky than that. I hoped something like this might have a chance to work: (defun colins-command () (interactive) (self-insert-internal ?\301) ;; Attempt No. 1 to fool isearch. (setq this-command 'self-insert-command)) ;; Attempt No. 2 to fool isearch. (put 'colins-command 'isearch-command t) (global-set-key [(alt a)] 'colins-command) But it doesn't work because isearch-maybe-frob-keyboard-macros, which gets called from isearch-pre-command-hook, i.e. *before* your function is run, explicitly checks for self-insert-command. I was tempted to try to "fix" isearch-maybe-frob-keyboard-macros, but after some thinking I concluded that it was the only reasonable thing to do. Remember that isearch needs to update its search string with the new character. Isearch cannot know in advance what character colins-command is about to insert; since colins-command is not self-insert-command, just using last-command-event would be wrong. But then I remembered that "keysyms" aren't really cast in stone, and that with a little trickery you can fake keysyms from Lisp. Here is the result: (global-set-key '(alt a) [fake-keysym]) (global-set-key 'fake-keysym 'self-insert-command) (put 'fake-keysym 'ascii-character ?\301)