diff --git a/doc/irc.luadoc b/doc/irc.luadoc
index c8c5d8e..58a320a 100644
--- a/doc/irc.luadoc
+++ b/doc/irc.luadoc
@@ -25,8 +25,9 @@
 module "irc"
 
 --- Create a new IRC object. Use <code>irc:connect</code> to connect to a server.
--- @param user Table with fields <code>nick</code>, <code>username</code> and <code>realname</code>.
+-- @param user Table with fields <code>nick</code>, <code>username</code>, <code>realname</code>, and <code>nick_generator</code>.
 -- The <code>nick</code> field is required.
+-- The <code>nick_generator</code> field is a fuction that should return a new nick name given the old one.
 --
 -- @return Returns a new <code>irc</code> object.
 function new(user)
diff --git a/handlers.lua b/handlers.lua
index 6b892f9..4d4a28b 100644
--- a/handlers.lua
+++ b/handlers.lua
@@ -96,6 +96,18 @@ handlers["366"] = function(o, prefix, me, channel, msg)
 	end
 end
 
+local function handle_bad_nick(o, prefix, x, badnick)
+	o.nick = o.nick_generator(badnick)
+	o.send("NICK %s", o.nick)
+	o.send("USER %s 0 * :%s", o.username, o.realname)
+end
+
+-- ERR_ERRONEOUSNICKNAME
+handlers["432"] = handle_bad_nick
+
+-- ERR_NICKNAMEINUSE
+handlers["433"] = handle_bad_nick
+
 --no topic
 handlers["331"] = function(o, prefix, me, channel)
 	o:invoke("OnTopic", channel, nil)
diff --git a/init.lua b/init.lua
index e94aa24..1b43e5b 100644
--- a/init.lua
+++ b/init.lua
@@ -38,6 +38,8 @@ function new(user)
 		realname = user.realname or "Lua owns";
 		hooks = {};
 		track_users = true;
+		nick_generator = user.nick_generator or
+				function(oldnick) error("Nick already in use.") end
 	}
 	return setmetatable(o, meta_preconnect)
 end