Missing ‘lexical-binding’ cookie in markup-faces.el

[maidentaiwan]

On startup in Emacs 31.1, I get this error message:

⛔ Warning (files): Missing ‘lexical-binding’ cookie in "<path>/markup-faces.el".
You can add one with ‘M-x elisp-enable-lexical-binding RET’.
See ‘(elisp)Selecting Lisp Dialect’ and ‘(elisp)Converting to Lexical Binding’
for more information.

[maidentaiwan]

I believe the fix is just to add this as the first line of the file:

;; -*- lexical-binding: t; -*-