diff --git a/etc/HELLO b/etc/HELLO
index ae52e94b065..f424a2ab8aa 100644
--- a/etc/HELLO
+++ b/etc/HELLO
@@ -96,4 +96,5 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 ;;; tab-width: 32
 ;;; bidi-display-reordering: t
 ;;; coding: iso-2022-7bit
+;;; inhibit-compacting-font-caches: t
 ;;; End:
diff --git a/lisp/files.el b/lisp/files.el
index f3b502095dd..2187eba1a42 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3233,6 +3233,7 @@ asking you for confirmation."
 	   (fill-column             . integerp)	;; C source code
 	   (indent-tabs-mode        . booleanp)	;; C source code
 	   (left-margin             . integerp)	;; C source code
+	   (inhibit-compacting-font-caches . booleanp) ;; C source code
 	   (no-update-autoloads     . booleanp)
 	   (lexical-binding	 . booleanp)	  ;; C source code
 	   (tab-width               . integerp)	  ;; C source code