On the emacs-25 and master branches, changing the syntax-table temporarily affects the table used during syntax-propertize. This does not happen in 24.5 (unless the difference is just a timing thing?). This triggers an infinite loop when expanding certain snippets with yasnippet in haskell-mode (see [1] and [2]). Attached is a simplified reproducer, run as emacs -Q -l synprop-bug.el In Emacs 25+, this results in the message Error during redisplay: (internal--syntax-propertize 2) signaled (error "syntax table is changed to standard-syntax-table during syntax propertize") In Emacs 24.5, it runs without a problem. It's not entirely clear to me who should be reponsible for ensuring the right syntax-table during syntax-propertize. [1]: https://github.com/capitaomorte/yasnippet/issues/687 [2]: https://github.com/haskell/haskell-mode/issues/1315