diff --git a/lisp/calendar/calendar.el b/lisp/calendar/calendar.el
index fbc176470ce..659b6610d06 100644
--- a/lisp/calendar/calendar.el
+++ b/lisp/calendar/calendar.el
@@ -1,4 +1,4 @@
-;;; calendar.el --- Calendar functions.
+;;; calendar.el --- Calendar functions.  -*-byte-compile-dynamic: t;-*-
 
 ;;; Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994 Free Software
 ;;; Foundation, Inc.