Use add-hook instead of setq.

diff --git a/lisp/calendar/appt.el b/lisp/calendar/appt.el
index 02131a34add8b60cff0f60174c6008ab964d1f83..d616fae71d0aae5a512043f75f7617ee1a836463 100644 (file)
--- a/lisp/calendar/appt.el
+++ b/lisp/calendar/appt.el
@@ -568,7 +568,7 @@ The time should be in either 24 hour format or am/pm format."
     (setq conv-time (+ (* hr 60) min))
     conv-time))
 
-(setq display-time-hook 'appt-check)
+(add-hook 'display-time-hook 'appt-check)
 
 ;;; appt.el ends here