diff --git a/lisp/time.el b/lisp/time.el
index 58e1dd486fb..49b9c604ae0 100644
--- a/lisp/time.el
+++ b/lisp/time.el
@@ -36,8 +36,8 @@
 
 (defcustom display-time-mode nil
   "Toggle display of time, load level, and mail flag in mode lines.
-This variable should be set only with \\[customize], which is equivalent
-to using the function `display-time-mode'."
+Setting this variable directly does not take effect;
+use either \\[customize] or the function `display-time-mode'."
   :set (lambda (symbol value)
 	 (display-time-mode (or value 0)))
   :initialize 'custom-initialize-default