Even though I have the following customizations in place '(comment-multi-line t) '(comment-style (quote extra-line)) comment-region command produces this /* some comment */ rather than this /* * some comment */ Attached is a patch that I use to fix the issue on my workstation. Besides fixing the (supposed) off-by-one error, the patch also removes trailing whitespace from the initial line of the comment ("/* "). (My knowledge of Elisp is not too advanced so I wonder if there's simpler way to trim whitespace from a string.) In GNU Emacs 25.2.3 (x86_64-suse-linux-gnu, X toolkit, Xaw scroll bars) of 2017-03-10 built on linux-j735 Repository revision: 6e788ef0e262fafc014c21f4ad52cc5dc9f1715b Windowing system distributor 'The X.Org Foundation', version 11.0.11702000 System Description: openSUSE Leap 42.1 (x86_64) Configured using: 'configure --prefix=/home/ah/emacs 'CC=ccache cc'' Configured features: XPM JPEG TIFF GIF PNG SOUND NOTIFY GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS LUCID X11 Important settings: value of $EMACSLOADPATH: :/home/ah/repos/pgqa/lisp/pgqa value of $LANG: en_US.UTF-8 value of $XMODIFIERS: @im=local locale-coding-system: utf-8-unix Major mode: Messages Minor modes in effect: tooltip-mode: t global-eldoc-mode: t electric-indent-mode: t mouse-wheel-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t buffer-read-only: t column-number-mode: t line-number-mode: t global-visual-line-mode: t visual-line-mode: t transient-mark-mode: t Recent messages: Loading delsel...done For information about GNU Emacs and the GNU system, type C-h C-a. 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