An infinite loop occurs when Subword mode is active and `studlify-word' is run on a word with more than one subword. The bug seems to have been introduced by changes made to subword.el in commit 6ddc44225e743e2b2a0d5c192f50aefd7a4a915b. Here is a recipe that triggers the bug, starting from emacs -Q: 1. Open a new buffer, and type in "subWord". 2. Activate Subword mode by `M-x subword-mode'. 3. Move point to the beginning of the line, and run `M-x studlify-word'. In GNU Emacs 25.0.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5) of 2015-02-24 on x240 Repository revision: 450bebaec94611f0958e13e35faf494e17931f8e Windowing system distributor `The X.Org Foundation', version 11.0.11604000 System Description: Debian GNU/Linux 8.0 (jessie) Configured using: `configure --without-makeinfo' Configured features: XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY LIBXML2 FREETYPE XFT ZLIB Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t global-eldoc-mode: t electric-indent-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-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 line-number-mode: t Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Load-path shadows: None found. Features: (shadow sort gnus-util mail-extr emacsbug message dired format-spec rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils time-date tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process dbusbind gfilenotify dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs) Memory information: ((conses 16 74956 6410) (symbols 48 18012 0) (miscs 40 43 124) (strings 32 10961 5159) (string-bytes 1 296944) (vectors 16 9377) (vector-slots 8 386766 15535) (floats 8 70 63) (intervals 56 175 0) (buffers 976 11) (heap 1024 31954 1039))