Hi, Windows 7 Emacs git master/2018.6.24 at least When I try to toggle hexl-mode, it reports "defvar: Symbol's value as variable is void: hexl-follow-ascii-mode". It looks like the definiation of hexl-follow-ascii-mode is incorect. From the doc of define-minor-mode, it requires INIT-VALUE LIGHTER KEYMAP or at least one keyword argument. According to the DOC of hexl-follow-ascii-mode, I think the following patch should be proper. diff --git a/lisp/hexl.el b/lisp/hexl.el index f37be9d410..6b316dd707 100644 --- a/lisp/hexl.el +++ b/lisp/hexl.el @@ -1000,6 +1000,7 @@ hexl-follow-ascii-mode When following is enabled, the ASCII character corresponding to the element under the point is highlighted. The default activation is controlled by `hexl-follow-ascii'." + :init-value hexl-follow-ascii (if hexl-follow-ascii-mode ;; turn it on (progn Best Regards, Shuguang Sun