1 files changed, 8 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/syntax.el b/lisp/emacs-lisp/syntax.el
index a1b70b18693..6106720f7a5 100644
--- a/lisp/emacs-lisp/syntax.el
+++ b/lisp/emacs-lisp/syntax.el
@@ -291,6 +291,14 @@ END) suitable for `syntax-propertize-function'."
       ;; (message "Needs to syntax-propertize from %s to %s"
       ;;          syntax-propertize--done pos)
       (set (make-local-variable 'parse-sexp-lookup-properties) t)
+      (when (< syntax-propertize--done (point-min))
+        ;; *Usually* syntax-propertize is called via syntax-ppss which
+        ;; takes care of adding syntax-ppss-flush-cache to b-c-f, but this
+        ;; is not *always* the case, so since we share a single "flush" function
+        ;; between syntax-ppss and syntax-propertize, we also have to make
+        ;; sure the flush function is installed here (bug#29767).
+        (add-hook 'before-change-functions
+                  #'syntax-ppss-flush-cache t t))
       (save-excursion
         (with-silent-modifications
           (make-local-variable 'syntax-propertize--done) ;Just in case!