diff --git a/etc/NEWS b/etc/NEWS
index 6d039bac4a8..bf942cb1872 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2853,6 +2853,11 @@ The new '/opme' convenience command asks ChanServ to set the operator
 status for the current nick in the current channel, and '/deopme'
 unsets it.
 
+---
+*** Fix the order of '/whois' arguments sent to the server.
+Per RFC 1459 and RFC 2812, when given, the optional 'server' argument
+for the WHOIS command must come before the 'user' argument, not after.
+
 ** xwidget-webkit mode
 
 ---
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index ac0c08bd3a2..7fa2d37c9f2 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -3301,10 +3301,13 @@ a script after exceeding the flood threshold."
 (defun erc-cmd-WHOIS (user &optional server)
   "Display whois information for USER.
 
-If SERVER is non-nil, use that, rather than the current server."
-  ;; FIXME: is the above docstring correct?  -- Lawrence 2004-01-08
+If SERVER is non-nil, use that, rather than the current server.
+This is useful for getting the time USER has been idle for, if
+USER is on a different server of the network than the current
+user, since only the server the user is connected to knows this
+information."
   (let ((send (if server
-                  (format "WHOIS %s %s" user server)
+                  (format "WHOIS %s %s" server user)
                 (format "WHOIS %s" user))))
     (erc-log (format "cmd: %s" send))
     (erc-server-send send)