1 files changed, 1 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 7d47d809673..940b4869f51 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -1121,6 +1121,7 @@
 (put 'symbol-name 'byte-optimizer 'byte-optimize-pure-func)
 (put 'regexp-opt 'byte-optimizer 'byte-optimize-pure-func)
 (put 'regexp-quote 'byte-optimizer 'byte-optimize-pure-func)
+(put 'string-to-syntax 'byte-optimizer 'byte-optimize-pure-func)
 (defun byte-optimize-pure-func (form)
   "Do constant folding for pure functions.
 This assumes that the function will not have any side-effects and that