diff --git a/lisp/international/ucs-normalize.el b/lisp/international/ucs-normalize.el
index e212e14671e..9d55470d948 100644
--- a/lisp/international/ucs-normalize.el
+++ b/lisp/international/ucs-normalize.el
@@ -30,7 +30,7 @@
 ;;
 ;; HFS-Normalization:
 ;; Reference:
-;; http://developer.apple.com/technotes/tn/tn1150.html
+;; https://developer.apple.com/library/archive/technotes/tn/tn1150.html
 ;;
 ;; HFS Normalization excludes following area for decomposition.
 ;;