diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi
index 9b6752c5e1a..438f48c3471 100644
--- a/doc/lispref/os.texi
+++ b/doc/lispref/os.texi
@@ -2707,7 +2707,10 @@ This does not depend on one of the libraries linked to Emacs.
 
 Since all these libraries emit different events on notified file
 changes, there is the Emacs library @code{filenotify} which provides a
-unique interface.
+unified interface.  Lisp programs that want to receive file
+notifications should always use this library in preference to the
+native ones.
+
 
 @defun file-notify-add-watch file flags callback
 Add a watch for filesystem events pertaining to @var{file}.  This