diff --git a/irc/channel.go b/irc/channel.go
index cbc837a2..fed224aa 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -2,21 +2,18 @@ package irc
 
 import (
 	"log"
-	"sync"
 )
 
 type Channel struct {
-	banList   []UserMask
-	commands  chan<- ChannelCommand
-	destroyed bool
-	flags     map[ChannelMode]bool
-	key       string
-	members   ClientSet
-	mutex     *sync.Mutex
-	name      string
-	replies   chan<- Reply
-	server    *Server
-	topic     string
+	banList  []UserMask
+	commands chan<- ChannelCommand
+	flags    ChannelModeSet
+	key      string
+	members  MemberSet
+	name     string
+	replies  chan<- Reply
+	server   *Server
+	topic    string
 }
 
 func IsChannel(target string) bool {
@@ -38,9 +35,8 @@ func NewChannel(s *Server, name string) *Channel {
 	channel := &Channel{
 		banList:  make([]UserMask, 0),
 		commands: commands,
-		flags:    make(map[ChannelMode]bool),
-		members:  make(ClientSet),
-		mutex:    &sync.Mutex{},
+		flags:    make(ChannelModeSet),
+		members:  make(MemberSet),
 		name:     name,
 		replies:  replies,
 		server:   s,
@@ -50,19 +46,17 @@ func NewChannel(s *Server, name string) *Channel {
 	return channel
 }
 
+type DestroyChannel struct {
+	BaseCommand
+	channel *Channel
+}
+
 func (channel *Channel) Destroy() {
-	if channel.IsDestroyed() {
-		return
-	}
-
-	channel.withMutex(func() {
-		channel.destroyed = true
-		channel.members = make(ClientSet)
-	})
-
-	channel.server.withMutex(func() {
-		channel.server.channels.Remove(channel)
+	channel.server.Command(&DestroyChannel{
+		channel: channel,
 	})
+	close(channel.commands)
+	close(channel.replies)
 }
 
 func (channel *Channel) Command(command ChannelCommand) {
@@ -75,13 +69,6 @@ func (channel *Channel) Reply(reply Reply) {
 
 func (channel *Channel) receiveCommands(commands <-chan ChannelCommand) {
 	for command := range commands {
-		if channel.IsDestroyed() {
-			if DEBUG_CHANNEL {
-				log.Printf("%s → %s %s dropped", command.Source(), channel, command)
-			}
-			continue
-		}
-
 		if DEBUG_CHANNEL {
 			log.Printf("%s → %s %s", command.Source(), channel, command)
 		}
@@ -89,40 +76,19 @@ func (channel *Channel) receiveCommands(commands <-chan ChannelCommand) {
 	}
 }
 
-func IsPrivMsg(reply Reply) bool {
-	strReply, ok := reply.(*StringReply)
-	if !ok {
-		return false
-	}
-	return strReply.code == "PRIVMSG"
-}
-
-func (channel *Channel) IsDestroyed() bool {
-	channel.mutex.Lock()
-	defer channel.mutex.Unlock()
-	return channel.destroyed
-}
-
 func (channel *Channel) receiveReplies(replies <-chan Reply) {
 	for reply := range replies {
-		if channel.IsDestroyed() {
-			if DEBUG_CHANNEL {
-				log.Printf("%s ← %s %s dropped", channel, reply.Source(), reply)
-			}
-			continue
-		}
-
 		if DEBUG_CHANNEL {
 			log.Printf("%s ← %s %s", channel, reply.Source(), reply)
 		}
-		channel.withMutex(func() {
-			for client := range channel.members {
-				if IsPrivMsg(reply) && (reply.Source() == Identifier(client)) {
-					continue
-				}
-				client.Reply(reply)
+
+		for client := range channel.members {
+			if (reply.Code() == ReplyCode(PRIVMSG)) &&
+				(reply.Source() == Identifier(client)) {
+				continue
 			}
-		})
+			client.Reply(reply)
+		}
 	}
 }
 
@@ -198,25 +164,9 @@ func (channel *Channel) ModeString() (str string) {
 	return
 }
 
-func (channel *Channel) withMutex(f func()) {
-	channel.mutex.Lock()
-	defer channel.mutex.Unlock()
-	f()
-}
-
-func (channel *Channel) Join(client *Client) {
-	channel.withMutex(func() {
-		channel.members.Add(client)
-		if len(channel.members) == 1 {
-			channel.members[client][ChannelCreator] = true
-			channel.members[client][ChannelOperator] = true
-		}
-		client.channels.Add(channel)
-	})
-
-	channel.Reply(RplJoin(client, channel))
-	channel.GetTopic(client)
-	channel.GetUsers(client)
+type JoinChannel struct {
+	BaseCommand
+	channel *Channel
 }
 
 //
@@ -230,7 +180,33 @@ func (m *JoinCommand) HandleChannel(channel *Channel) {
 		return
 	}
 
-	channel.Join(client)
+	channel.members.Add(client)
+	if len(channel.members) == 1 {
+		channel.members[client][ChannelCreator] = true
+		channel.members[client][ChannelOperator] = true
+	}
+
+	client.commands <- &JoinChannel{
+		channel: channel,
+	}
+
+	addClient := &AddFriend{
+		client: client,
+	}
+	for member := range channel.members {
+		client.commands <- &AddFriend{
+			client: member,
+		}
+		member.commands <- addClient
+	}
+
+	channel.Reply(RplJoin(client, channel))
+	channel.GetTopic(client)
+	channel.GetUsers(client)
+}
+
+type PartChannel struct {
+	channel *Channel
 }
 
 func (m *PartCommand) HandleChannel(channel *Channel) {
@@ -244,9 +220,15 @@ func (m *PartCommand) HandleChannel(channel *Channel) {
 	channel.Reply(RplPart(client, channel, m.Message()))
 
 	channel.members.Remove(client)
-	client.channels.Remove(channel)
+	client.commands <- &PartChannel{
+		channel: channel,
+	}
+	for member := range channel.members {
+		member.commands <- &RemoveFriend{
+			client: client,
+		}
+	}
 
-	// TODO persistent channels
 	if channel.IsEmpty() {
 		channel.Destroy()
 	}
@@ -387,3 +369,18 @@ func (m *NoticeCommand) HandleChannel(channel *Channel) {
 	}
 	channel.Reply(RplNotice(client, channel, m.message))
 }
+
+func (msg *QuitCommand) HandleChannel(channel *Channel) {
+	client := msg.Client()
+	removeClient := &RemoveFriend{
+		client: client,
+	}
+	for member := range channel.members {
+		member.commands <- removeClient
+	}
+	channel.members.Remove(client)
+}
+
+func (msg *DestroyClient) HandleChannel(channel *Channel) {
+	channel.members.Remove(msg.client)
+}
diff --git a/irc/client.go b/irc/client.go
index 04b5bc1a..a7887b6b 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"log"
 	"net"
-	"sync"
 	"time"
 )
 
@@ -13,13 +12,13 @@ type Client struct {
 	away        bool
 	awayMessage string
 	channels    ChannelSet
+	commands    chan ClientCommand
 	ctime       time.Time
-	destroyed   bool
+	friends     map[*Client]uint
 	hostname    string
 	idleTimer   *time.Timer
 	invisible   bool
 	loginTimer  *time.Timer
-	mutex       *sync.Mutex
 	nick        string
 	operator    bool
 	phase       Phase
@@ -36,16 +35,18 @@ func NewClient(server *Server, conn net.Conn) *Client {
 	client := &Client{
 		atime:    now,
 		channels: make(ChannelSet),
+		commands: make(chan ClientCommand),
 		ctime:    now,
+		friends:  make(map[*Client]uint),
 		hostname: AddrLookupHostname(conn.RemoteAddr()),
 		phase:    server.InitPhase(),
 		replies:  make(chan Reply),
 		server:   server,
 		socket:   NewSocket(conn),
-		mutex:    &sync.Mutex{},
 	}
-	client.loginTimer = time.AfterFunc(LOGIN_TIMEOUT, client.Destroy)
 
+	client.loginTimer = time.AfterFunc(LOGIN_TIMEOUT, client.Destroy)
+	go client.readClientCommands()
 	go client.readCommands()
 	go client.writeReplies()
 
@@ -53,10 +54,6 @@ func NewClient(server *Server, conn net.Conn) *Client {
 }
 
 func (client *Client) Touch() {
-	if client.IsDestroyed() {
-		return
-	}
-
 	client.atime = time.Now()
 
 	if client.quitTimer != nil {
@@ -89,10 +86,6 @@ func (client *Client) ConnectionTimeout() {
 }
 
 func (client *Client) ConnectionClosed() {
-	if client.IsDestroyed() {
-		return
-	}
-
 	msg := &QuitCommand{
 		message: "connection closed",
 	}
@@ -100,6 +93,12 @@ func (client *Client) ConnectionClosed() {
 	client.server.Command(msg)
 }
 
+func (client *Client) readClientCommands() {
+	for command := range client.commands {
+		command.HandleClient(client)
+	}
+}
+
 func (c *Client) readCommands() {
 	for line := range c.socket.Read() {
 		m, err := ParseCommand(line)
@@ -126,13 +125,6 @@ func (c *Client) readCommands() {
 
 func (client *Client) writeReplies() {
 	for reply := range client.replies {
-		if client.IsDestroyed() {
-			if DEBUG_CLIENT {
-				log.Printf("%s ← %s dropped", client, reply)
-			}
-			continue
-		}
-
 		if DEBUG_CLIENT {
 			log.Printf("%s ← %s", client, reply)
 		}
@@ -143,24 +135,12 @@ func (client *Client) writeReplies() {
 	}
 }
 
-func (client *Client) IsDestroyed() bool {
-	client.mutex.Lock()
-	defer client.mutex.Unlock()
-	return client.destroyed
+type DestroyClient struct {
+	BaseCommand
+	client *Client
 }
 
 func (client *Client) Destroy() {
-	if client.IsDestroyed() {
-		return
-	}
-
-	if DEBUG_CLIENT {
-		log.Printf("%s destroying", client)
-	}
-
-	client.mutex.Lock()
-	client.destroyed = true
-
 	client.socket.Close()
 
 	if client.idleTimer != nil {
@@ -171,14 +151,15 @@ func (client *Client) Destroy() {
 		client.quitTimer.Stop()
 	}
 
-	client.channels = make(ChannelSet) // clear channel list
-	client.server.clients.Remove(client)
-
-	client.mutex.Unlock()
-
-	if DEBUG_CLIENT {
-		log.Printf("%s destroyed", client)
+	cmd := &DestroyClient{
+		client: client,
 	}
+
+	for channel := range client.channels {
+		channel.Command(cmd)
+	}
+
+	client.server.Command(cmd)
 }
 
 func (client *Client) Reply(reply Reply) {
@@ -199,16 +180,6 @@ func (client *Client) HasUsername() bool {
 	return client.username != ""
 }
 
-func (client *Client) InterestedClients() ClientSet {
-	clients := make(ClientSet)
-	for channel := range client.channels {
-		for member := range channel.members {
-			clients.Add(member)
-		}
-	}
-	return clients
-}
-
 // <mode>
 func (c *Client) ModeString() (str string) {
 	if c.invisible {
@@ -246,3 +217,63 @@ func (c *Client) Id() string {
 func (c *Client) String() string {
 	return c.UserHost()
 }
+
+//
+// commands
+//
+
+type AddFriend struct {
+	client *Client
+}
+
+func (msg *AddFriend) HandleClient(client *Client) {
+	client.friends[msg.client] += 1
+}
+
+type RemoveFriend struct {
+	client *Client
+}
+
+func (msg *RemoveFriend) HandleClient(client *Client) {
+	client.friends[msg.client] -= 1
+	if client.friends[msg.client] <= 0 {
+		delete(client.friends, msg.client)
+	}
+}
+
+func (msg *JoinChannel) HandleClient(client *Client) {
+	client.channels.Add(msg.channel)
+}
+
+func (msg *PartChannel) HandleClient(client *Client) {
+	client.channels.Remove(msg.channel)
+}
+
+func (msg *NickCommand) HandleClient(client *Client) {
+	// Make reply before changing nick.
+	reply := RplNick(client, msg.nickname)
+
+	client.nick = msg.nickname
+
+	for friend := range client.friends {
+		friend.Reply(reply)
+	}
+}
+
+func (msg *QuitCommand) HandleClient(client *Client) {
+	if len(client.friends) > 0 {
+		reply := RplQuit(client, msg.message)
+		for friend := range client.friends {
+			if friend == client {
+				continue
+			}
+			friend.Reply(reply)
+		}
+	}
+
+	for channel := range client.channels {
+		channel.commands <- msg
+	}
+
+	client.Destroy()
+}
diff --git a/irc/constants.go b/irc/constants.go
index 0ef8bd87..710c3398 100644
--- a/irc/constants.go
+++ b/irc/constants.go
@@ -23,143 +23,157 @@ const (
 	IDLE_TIMEOUT  = time.Minute     // how long before a client is considered idle
 	QUIT_TIMEOUT  = time.Minute     // how long after idle before a client is kicked
 
+	// string codes
+	PRIVMSG StringCode = "PRIVMSG"
+	NOTICE  StringCode = "NOTICE"
+	NICK    StringCode = "NICK"
+	JOIN    StringCode = "JOIN"
+	PART    StringCode = "PART"
+	MODE    StringCode = "MODE"
+	TOPIC   StringCode = "TOPIC"
+	PING    StringCode = "PING"
+	PONG    StringCode = "PONG"
+	QUIT    StringCode = "QUIT"
+	ERROR   StringCode = "ERROR"
+	INVITE  StringCode = "INVITE"
+
 	// numeric codes
-	RPL_WELCOME           Numeric = 1
-	RPL_YOURHOST          Numeric = 2
-	RPL_CREATED           Numeric = 3
-	RPL_MYINFO            Numeric = 4
-	RPL_BOUNCE            Numeric = 5
-	RPL_TRACELINK         Numeric = 200
-	RPL_TRACECONNECTING   Numeric = 201
-	RPL_TRACEHANDSHAKE    Numeric = 202
-	RPL_TRACEUNKNOWN      Numeric = 203
-	RPL_TRACEOPERATOR     Numeric = 204
-	RPL_TRACEUSER         Numeric = 205
-	RPL_TRACESERVER       Numeric = 206
-	RPL_TRACESERVICE      Numeric = 207
-	RPL_TRACENEWTYPE      Numeric = 208
-	RPL_TRACECLASS        Numeric = 209
-	RPL_TRACERECONNECT    Numeric = 210
-	RPL_STATSLINKINFO     Numeric = 211
-	RPL_STATSCOMMANDS     Numeric = 212
-	RPL_ENDOFSTATS        Numeric = 219
-	RPL_UMODEIS           Numeric = 221
-	RPL_SERVLIST          Numeric = 234
-	RPL_SERVLISTEND       Numeric = 235
-	RPL_STATSUPTIME       Numeric = 242
-	RPL_STATSOLINE        Numeric = 243
-	RPL_LUSERCLIENT       Numeric = 251
-	RPL_LUSEROP           Numeric = 252
-	RPL_LUSERUNKNOWN      Numeric = 253
-	RPL_LUSERCHANNELS     Numeric = 254
-	RPL_LUSERME           Numeric = 255
-	RPL_ADMINME           Numeric = 256
-	RPL_ADMINLOC1         Numeric = 257
-	RPL_ADMINLOC2         Numeric = 258
-	RPL_ADMINEMAIL        Numeric = 259
-	RPL_TRACELOG          Numeric = 261
-	RPL_TRACEEND          Numeric = 262
-	RPL_TRYAGAIN          Numeric = 263
-	RPL_AWAY              Numeric = 301
-	RPL_USERHOST          Numeric = 302
-	RPL_ISON              Numeric = 303
-	RPL_UNAWAY            Numeric = 305
-	RPL_NOWAWAY           Numeric = 306
-	RPL_WHOISUSER         Numeric = 311
-	RPL_WHOISSERVER       Numeric = 312
-	RPL_WHOISOPERATOR     Numeric = 313
-	RPL_WHOWASUSER        Numeric = 314
-	RPL_ENDOFWHO          Numeric = 315
-	RPL_WHOISIDLE         Numeric = 317
-	RPL_ENDOFWHOIS        Numeric = 318
-	RPL_WHOISCHANNELS     Numeric = 319
-	RPL_LIST              Numeric = 322
-	RPL_LISTEND           Numeric = 323
-	RPL_CHANNELMODEIS     Numeric = 324
-	RPL_UNIQOPIS          Numeric = 325
-	RPL_NOTOPIC           Numeric = 331
-	RPL_TOPIC             Numeric = 332
-	RPL_INVITING          Numeric = 341
-	RPL_SUMMONING         Numeric = 342
-	RPL_INVITELIST        Numeric = 346
-	RPL_ENDOFINVITELIST   Numeric = 347
-	RPL_EXCEPTLIST        Numeric = 348
-	RPL_ENDOFEXCEPTLIST   Numeric = 349
-	RPL_VERSION           Numeric = 351
-	RPL_WHOREPLY          Numeric = 352
-	RPL_NAMREPLY          Numeric = 353
-	RPL_LINKS             Numeric = 364
-	RPL_ENDOFLINKS        Numeric = 365
-	RPL_ENDOFNAMES        Numeric = 366
-	RPL_BANLIST           Numeric = 367
-	RPL_ENDOFBANLIST      Numeric = 368
-	RPL_ENDOFWHOWAS       Numeric = 369
-	RPL_INFO              Numeric = 371
-	RPL_MOTD              Numeric = 372
-	RPL_ENDOFINFO         Numeric = 374
-	RPL_MOTDSTART         Numeric = 375
-	RPL_ENDOFMOTD         Numeric = 376
-	RPL_YOUREOPER         Numeric = 381
-	RPL_REHASHING         Numeric = 382
-	RPL_YOURESERVICE      Numeric = 383
-	RPL_TIME              Numeric = 391
-	RPL_USERSSTART        Numeric = 392
-	RPL_USERS             Numeric = 393
-	RPL_ENDOFUSERS        Numeric = 394
-	RPL_NOUSERS           Numeric = 395
-	ERR_NOSUCHNICK        Numeric = 401
-	ERR_NOSUCHSERVER      Numeric = 402
-	ERR_NOSUCHCHANNEL     Numeric = 403
-	ERR_CANNOTSENDTOCHAN  Numeric = 404
-	ERR_TOOMANYCHANNELS   Numeric = 405
-	ERR_WASNOSUCHNICK     Numeric = 406
-	ERR_TOOMANYTARGETS    Numeric = 407
-	ERR_NOSUCHSERVICE     Numeric = 408
-	ERR_NOORIGIN          Numeric = 409
-	ERR_NORECIPIENT       Numeric = 411
-	ERR_NOTEXTTOSEND      Numeric = 412
-	ERR_NOTOPLEVEL        Numeric = 413
-	ERR_WILDTOPLEVEL      Numeric = 414
-	ERR_BADMASK           Numeric = 415
-	ERR_UNKNOWNCOMMAND    Numeric = 421
-	ERR_NOMOTD            Numeric = 422
-	ERR_NOADMININFO       Numeric = 423
-	ERR_FILEERROR         Numeric = 424
-	ERR_NONICKNAMEGIVEN   Numeric = 431
-	ERR_ERRONEUSNICKNAME  Numeric = 432
-	ERR_NICKNAMEINUSE     Numeric = 433
-	ERR_NICKCOLLISION     Numeric = 436
-	ERR_UNAVAILRESOURCE   Numeric = 437
-	ERR_USERNOTINCHANNEL  Numeric = 441
-	ERR_NOTONCHANNEL      Numeric = 442
-	ERR_USERONCHANNEL     Numeric = 443
-	ERR_NOLOGIN           Numeric = 444
-	ERR_SUMMONDISABLED    Numeric = 445
-	ERR_USERSDISABLED     Numeric = 446
-	ERR_NOTREGISTERED     Numeric = 451
-	ERR_NEEDMOREPARAMS    Numeric = 461
-	ERR_ALREADYREGISTRED  Numeric = 462
-	ERR_NOPERMFORHOST     Numeric = 463
-	ERR_PASSWDMISMATCH    Numeric = 464
-	ERR_YOUREBANNEDCREEP  Numeric = 465
-	ERR_YOUWILLBEBANNED   Numeric = 466
-	ERR_KEYSET            Numeric = 467
-	ERR_CHANNELISFULL     Numeric = 471
-	ERR_UNKNOWNMODE       Numeric = 472
-	ERR_INVITEONLYCHAN    Numeric = 473
-	ERR_BANNEDFROMCHAN    Numeric = 474
-	ERR_BADCHANNELKEY     Numeric = 475
-	ERR_BADCHANMASK       Numeric = 476
-	ERR_NOCHANMODES       Numeric = 477
-	ERR_BANLISTFULL       Numeric = 478
-	ERR_NOPRIVILEGES      Numeric = 481
-	ERR_CHANOPRIVSNEEDED  Numeric = 482
-	ERR_CANTKILLSERVER    Numeric = 483
-	ERR_RESTRICTED        Numeric = 484
-	ERR_UNIQOPPRIVSNEEDED Numeric = 485
-	ERR_NOOPERHOST        Numeric = 491
-	ERR_UMODEUNKNOWNFLAG  Numeric = 501
-	ERR_USERSDONTMATCH    Numeric = 502
+	RPL_WELCOME           NumericCode = 1
+	RPL_YOURHOST          NumericCode = 2
+	RPL_CREATED           NumericCode = 3
+	RPL_MYINFO            NumericCode = 4
+	RPL_BOUNCE            NumericCode = 5
+	RPL_TRACELINK         NumericCode = 200
+	RPL_TRACECONNECTING   NumericCode = 201
+	RPL_TRACEHANDSHAKE    NumericCode = 202
+	RPL_TRACEUNKNOWN      NumericCode = 203
+	RPL_TRACEOPERATOR     NumericCode = 204
+	RPL_TRACEUSER         NumericCode = 205
+	RPL_TRACESERVER       NumericCode = 206
+	RPL_TRACESERVICE      NumericCode = 207
+	RPL_TRACENEWTYPE      NumericCode = 208
+	RPL_TRACECLASS        NumericCode = 209
+	RPL_TRACERECONNECT    NumericCode = 210
+	RPL_STATSLINKINFO     NumericCode = 211
+	RPL_STATSCOMMANDS     NumericCode = 212
+	RPL_ENDOFSTATS        NumericCode = 219
+	RPL_UMODEIS           NumericCode = 221
+	RPL_SERVLIST          NumericCode = 234
+	RPL_SERVLISTEND       NumericCode = 235
+	RPL_STATSUPTIME       NumericCode = 242
+	RPL_STATSOLINE        NumericCode = 243
+	RPL_LUSERCLIENT       NumericCode = 251
+	RPL_LUSEROP           NumericCode = 252
+	RPL_LUSERUNKNOWN      NumericCode = 253
+	RPL_LUSERCHANNELS     NumericCode = 254
+	RPL_LUSERME           NumericCode = 255
+	RPL_ADMINME           NumericCode = 256
+	RPL_ADMINLOC1         NumericCode = 257
+	RPL_ADMINLOC2         NumericCode = 258
+	RPL_ADMINEMAIL        NumericCode = 259
+	RPL_TRACELOG          NumericCode = 261
+	RPL_TRACEEND          NumericCode = 262
+	RPL_TRYAGAIN          NumericCode = 263
+	RPL_AWAY              NumericCode = 301
+	RPL_USERHOST          NumericCode = 302
+	RPL_ISON              NumericCode = 303
+	RPL_UNAWAY            NumericCode = 305
+	RPL_NOWAWAY           NumericCode = 306
+	RPL_WHOISUSER         NumericCode = 311
+	RPL_WHOISSERVER       NumericCode = 312
+	RPL_WHOISOPERATOR     NumericCode = 313
+	RPL_WHOWASUSER        NumericCode = 314
+	RPL_ENDOFWHO          NumericCode = 315
+	RPL_WHOISIDLE         NumericCode = 317
+	RPL_ENDOFWHOIS        NumericCode = 318
+	RPL_WHOISCHANNELS     NumericCode = 319
+	RPL_LIST              NumericCode = 322
+	RPL_LISTEND           NumericCode = 323
+	RPL_CHANNELMODEIS     NumericCode = 324
+	RPL_UNIQOPIS          NumericCode = 325
+	RPL_NOTOPIC           NumericCode = 331
+	RPL_TOPIC             NumericCode = 332
+	RPL_INVITING          NumericCode = 341
+	RPL_SUMMONING         NumericCode = 342
+	RPL_INVITELIST        NumericCode = 346
+	RPL_ENDOFINVITELIST   NumericCode = 347
+	RPL_EXCEPTLIST        NumericCode = 348
+	RPL_ENDOFEXCEPTLIST   NumericCode = 349
+	RPL_VERSION           NumericCode = 351
+	RPL_WHOREPLY          NumericCode = 352
+	RPL_NAMREPLY          NumericCode = 353
+	RPL_LINKS             NumericCode = 364
+	RPL_ENDOFLINKS        NumericCode = 365
+	RPL_ENDOFNAMES        NumericCode = 366
+	RPL_BANLIST           NumericCode = 367
+	RPL_ENDOFBANLIST      NumericCode = 368
+	RPL_ENDOFWHOWAS       NumericCode = 369
+	RPL_INFO              NumericCode = 371
+	RPL_MOTD              NumericCode = 372
+	RPL_ENDOFINFO         NumericCode = 374
+	RPL_MOTDSTART         NumericCode = 375
+	RPL_ENDOFMOTD         NumericCode = 376
+	RPL_YOUREOPER         NumericCode = 381
+	RPL_REHASHING         NumericCode = 382
+	RPL_YOURESERVICE      NumericCode = 383
+	RPL_TIME              NumericCode = 391
+	RPL_USERSSTART        NumericCode = 392
+	RPL_USERS             NumericCode = 393
+	RPL_ENDOFUSERS        NumericCode = 394
+	RPL_NOUSERS           NumericCode = 395
+	ERR_NOSUCHNICK        NumericCode = 401
+	ERR_NOSUCHSERVER      NumericCode = 402
+	ERR_NOSUCHCHANNEL     NumericCode = 403
+	ERR_CANNOTSENDTOCHAN  NumericCode = 404
+	ERR_TOOMANYCHANNELS   NumericCode = 405
+	ERR_WASNOSUCHNICK     NumericCode = 406
+	ERR_TOOMANYTARGETS    NumericCode = 407
+	ERR_NOSUCHSERVICE     NumericCode = 408
+	ERR_NOORIGIN          NumericCode = 409
+	ERR_NORECIPIENT       NumericCode = 411
+	ERR_NOTEXTTOSEND      NumericCode = 412
+	ERR_NOTOPLEVEL        NumericCode = 413
+	ERR_WILDTOPLEVEL      NumericCode = 414
+	ERR_BADMASK           NumericCode = 415
+	ERR_UNKNOWNCOMMAND    NumericCode = 421
+	ERR_NOMOTD            NumericCode = 422
+	ERR_NOADMININFO       NumericCode = 423
+	ERR_FILEERROR         NumericCode = 424
+	ERR_NONICKNAMEGIVEN   NumericCode = 431
+	ERR_ERRONEUSNICKNAME  NumericCode = 432
+	ERR_NICKNAMEINUSE     NumericCode = 433
+	ERR_NICKCOLLISION     NumericCode = 436
+	ERR_UNAVAILRESOURCE   NumericCode = 437
+	ERR_USERNOTINCHANNEL  NumericCode = 441
+	ERR_NOTONCHANNEL      NumericCode = 442
+	ERR_USERONCHANNEL     NumericCode = 443
+	ERR_NOLOGIN           NumericCode = 444
+	ERR_SUMMONDISABLED    NumericCode = 445
+	ERR_USERSDISABLED     NumericCode = 446
+	ERR_NOTREGISTERED     NumericCode = 451
+	ERR_NEEDMOREPARAMS    NumericCode = 461
+	ERR_ALREADYREGISTRED  NumericCode = 462
+	ERR_NOPERMFORHOST     NumericCode = 463
+	ERR_PASSWDMISMATCH    NumericCode = 464
+	ERR_YOUREBANNEDCREEP  NumericCode = 465
+	ERR_YOUWILLBEBANNED   NumericCode = 466
+	ERR_KEYSET            NumericCode = 467
+	ERR_CHANNELISFULL     NumericCode = 471
+	ERR_UNKNOWNMODE       NumericCode = 472
+	ERR_INVITEONLYCHAN    NumericCode = 473
+	ERR_BANNEDFROMCHAN    NumericCode = 474
+	ERR_BADCHANNELKEY     NumericCode = 475
+	ERR_BADCHANMASK       NumericCode = 476
+	ERR_NOCHANMODES       NumericCode = 477
+	ERR_BANLISTFULL       NumericCode = 478
+	ERR_NOPRIVILEGES      NumericCode = 481
+	ERR_CHANOPRIVSNEEDED  NumericCode = 482
+	ERR_CANTKILLSERVER    NumericCode = 483
+	ERR_RESTRICTED        NumericCode = 484
+	ERR_UNIQOPPRIVSNEEDED NumericCode = 485
+	ERR_NOOPERHOST        NumericCode = 491
+	ERR_UMODEUNKNOWNFLAG  NumericCode = 501
+	ERR_USERSDONTMATCH    NumericCode = 502
 
 	Add    ModeOp = '+'
 	List   ModeOp = '='
diff --git a/irc/reply.go b/irc/reply.go
index 54d2be27..a0cee495 100644
--- a/irc/reply.go
+++ b/irc/reply.go
@@ -15,11 +15,16 @@ func joinedLen(names []string) int {
 }
 
 type BaseReply struct {
+	code    ReplyCode
 	id      string
 	message string
 	source  Identifier
 }
 
+func (reply *BaseReply) Code() ReplyCode {
+	return reply.code
+}
+
 func (reply *BaseReply) SetSource(source Identifier) {
 	reply.id = source.Id()
 	reply.source = source
@@ -31,16 +36,14 @@ func (reply *BaseReply) Source() Identifier {
 
 type StringReply struct {
 	BaseReply
-	code string
 }
 
-func NewStringReply(source Identifier, code string,
+func NewStringReply(source Identifier, code StringCode,
 	format string, args ...interface{}) *StringReply {
-	reply := &StringReply{
-		code: code,
-	}
-	reply.SetSource(source)
+	reply := &StringReply{}
+	reply.code = code
 	reply.message = fmt.Sprintf(format, args...)
+	reply.SetSource(source)
 	return reply
 }
 
@@ -57,16 +60,14 @@ func (reply *StringReply) String() string {
 
 type NumericReply struct {
 	BaseReply
-	code Numeric
 }
 
-func NewNumericReply(source Identifier, code Numeric, format string,
+func NewNumericReply(source Identifier, code NumericCode, format string,
 	args ...interface{}) *NumericReply {
-	reply := &NumericReply{
-		code: code,
-	}
-	reply.SetSource(source)
+	reply := &NumericReply{}
+	reply.code = code
 	reply.message = fmt.Sprintf(format, args...)
+	reply.SetSource(source)
 	return reply
 }
 
@@ -92,7 +93,7 @@ func NewNamesReply(channel *Channel) Reply {
 	reply := &NamesReply{
 		channel: channel,
 	}
-	reply.SetSource(channel)
+	reply.SetSource(channel.server)
 	return reply
 }
 
@@ -107,14 +108,16 @@ func (reply *NamesReply) Format(client *Client) []string {
 	nicks := reply.channel.Nicks()
 	for to < len(nicks) {
 		if (from < (to - 1)) && tooLong(nicks[from:to]) {
-			lines = append(lines, RplNamReply(reply.channel, nicks[from:to-1]).Format(client)...)
+			lines = append(lines, RplNamReply(reply.channel,
+				nicks[from:to-1]).Format(client)...)
 			from, to = to-1, to
 		} else {
 			to += 1
 		}
 	}
 	if from < len(nicks) {
-		lines = append(lines, RplNamReply(reply.channel, nicks[from:]).Format(client)...)
+		lines = append(lines, RplNamReply(reply.channel,
+			nicks[from:]).Format(client)...)
 	}
 	lines = append(lines, RplEndOfNames(reply.channel).Format(client)...)
 	return lines
@@ -128,56 +131,56 @@ func (reply *NamesReply) String() string {
 // messaging replies
 
 func RplPrivMsg(source Identifier, target Identifier, message string) Reply {
-	return NewStringReply(source, "PRIVMSG", "%s :%s", target.Nick(), message)
+	return NewStringReply(source, PRIVMSG, "%s :%s", target.Nick(), message)
 }
 
 func RplNotice(source Identifier, target Identifier, message string) Reply {
-	return NewStringReply(source, "NOTICE", "%s :%s", target.Nick(), message)
+	return NewStringReply(source, NOTICE, "%s :%s", target.Nick(), message)
 }
 
 func RplNick(source Identifier, newNick string) Reply {
-	return NewStringReply(source, "NICK", newNick)
+	return NewStringReply(source, NICK, newNick)
 }
 
 func RplJoin(client *Client, channel *Channel) Reply {
-	return NewStringReply(client, "JOIN", channel.name)
+	return NewStringReply(client, JOIN, channel.name)
 }
 
 func RplPart(client *Client, channel *Channel, message string) Reply {
-	return NewStringReply(client, "PART", "%s :%s", channel, message)
+	return NewStringReply(client, PART, "%s :%s", channel, message)
 }
 
 func RplMode(client *Client, changes ModeChanges) Reply {
-	return NewStringReply(client, "MODE", "%s :%s", client.Nick(), changes)
+	return NewStringReply(client, MODE, "%s :%s", client.Nick(), changes)
 }
 
 func RplChannelMode(client *Client, channel *Channel,
 	changes ChannelModeChanges) Reply {
-	return NewStringReply(client, "MODE", "%s %s", channel, changes)
+	return NewStringReply(client, MODE, "%s %s", channel, changes)
 }
 
 func RplTopicMsg(source Identifier, channel *Channel) Reply {
-	return NewStringReply(source, "TOPIC", "%s :%s", channel, channel.topic)
+	return NewStringReply(source, TOPIC, "%s :%s", channel, channel.topic)
 }
 
 func RplPing(server *Server, target Identifier) Reply {
-	return NewStringReply(server, "PING", target.Nick())
+	return NewStringReply(server, PING, target.Nick())
 }
 
 func RplPong(server *Server, client *Client) Reply {
-	return NewStringReply(server, "PONG", client.Nick())
+	return NewStringReply(server, PONG, client.Nick())
 }
 
 func RplQuit(client *Client, message string) Reply {
-	return NewStringReply(client, "QUIT", ":%s", message)
+	return NewStringReply(client, QUIT, ":%s", message)
 }
 
 func RplError(server *Server, target Identifier) Reply {
-	return NewStringReply(server, "ERROR", target.Nick())
+	return NewStringReply(server, ERROR, target.Nick())
 }
 
 func RplInviteMsg(channel *Channel, inviter *Client) Reply {
-	return NewStringReply(inviter, "INVITE", channel.name)
+	return NewStringReply(inviter, INVITE, channel.name)
 }
 
 // numeric replies
diff --git a/irc/server.go b/irc/server.go
index 10a5cb32..5a12fda4 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -9,20 +9,18 @@ import (
 	"log"
 	"net"
 	"os"
-	"sync"
 	"time"
 )
 
 type Server struct {
 	channels  ChannelNameMap
+	clients   ClientNameMap
 	commands  chan Command
 	ctime     time.Time
 	motdFile  string
-	mutex     *sync.Mutex
 	name      string
 	operators map[string]string
 	password  string
-	clients   ClientNameMap
 }
 
 func NewServer(config *Config) *Server {
@@ -32,7 +30,6 @@ func NewServer(config *Config) *Server {
 		commands:  make(chan Command),
 		ctime:     time.Now(),
 		motdFile:  config.MOTD,
-		mutex:     &sync.Mutex{},
 		name:      config.Name,
 		operators: make(map[string]string),
 		password:  config.Password,
@@ -43,7 +40,6 @@ func NewServer(config *Config) *Server {
 	}
 
 	go server.receiveCommands()
-
 	for _, listenerConf := range config.Listeners {
 		go server.listen(listenerConf)
 	}
@@ -51,12 +47,6 @@ func NewServer(config *Config) *Server {
 	return server
 }
 
-func (server *Server) withMutex(f func()) {
-	server.mutex.Lock()
-	defer server.mutex.Unlock()
-	f()
-}
-
 func (server *Server) receiveCommands() {
 	for command := range server.commands {
 		if DEBUG_SERVER {
@@ -145,9 +135,7 @@ func (s *Server) GetOrMakeChannel(name string) *Channel {
 
 	if !ok {
 		channel = NewChannel(s, name)
-		s.withMutex(func() {
-			s.channels[name] = channel
-		})
+		s.channels[name] = channel
 	}
 
 	return channel
@@ -316,17 +304,9 @@ func (m *NickCommand) HandleServer(s *Server) {
 		return
 	}
 
-	// Make reply before changing nick.
-	reply := RplNick(c, m.nickname)
-
 	s.clients.Remove(c)
-	c.nick = m.nickname
+	c.commands <- m
 	s.clients.Add(c)
-
-	iclients := c.InterestedClients()
-	for iclient := range iclients {
-		iclient.Reply(reply)
-	}
 }
 
 func (m *UserMsgCommand) HandleServer(s *Server) {
@@ -335,24 +315,10 @@ func (m *UserMsgCommand) HandleServer(s *Server) {
 
 func (m *QuitCommand) HandleServer(server *Server) {
 	client := m.Client()
-	iclients := client.InterestedClients()
-	iclients.Remove(client)
 
-	for channel := range client.channels {
-		channel.withMutex(func() {
-			channel.members.Remove(client)
-		})
-	}
+	server.clients.Remove(client)
 
-	client.Reply(RplError(server, client))
-	client.Destroy()
-
-	if len(iclients) > 0 {
-		reply := RplQuit(client, m.message)
-		for iclient := range iclients {
-			iclient.Reply(reply)
-		}
-	}
+	client.commands <- m
 }
 
 func (m *JoinCommand) HandleServer(s *Server) {
@@ -374,9 +340,7 @@ func (m *JoinCommand) HandleServer(s *Server) {
 
 func (m *PartCommand) HandleServer(server *Server) {
 	for _, chname := range m.channels {
-		server.mutex.Lock()
 		channel := server.channels[chname]
-		server.mutex.Unlock()
 
 		if channel == nil {
 			m.Client().Reply(ErrNoSuchChannel(server, chname))
@@ -567,3 +531,11 @@ func (msg *NoticeCommand) HandleServer(server *Server) {
 	}
 	target.Reply(RplPrivMsg(msg.Client(), target, msg.message))
 }
+
+func (msg *DestroyChannel) HandleServer(server *Server) {
+	server.channels.Remove(msg.channel)
+}
+
+func (msg *DestroyClient) HandleServer(server *Server) {
+	server.clients.Remove(msg.client)
+}
diff --git a/irc/types.go b/irc/types.go
index 554f5093..9ce6b236 100644
--- a/irc/types.go
+++ b/irc/types.go
@@ -28,9 +28,19 @@ func (mode UserMode) String() string {
 
 type Phase uint
 
-type Numeric uint
+type ReplyCode interface {
+	String() string
+}
 
-func (code Numeric) String() string {
+type StringCode string
+
+func (code StringCode) String() string {
+	return string(code)
+}
+
+type NumericCode uint
+
+func (code NumericCode) String() string {
 	return fmt.Sprintf("%03d", code)
 }
 
@@ -87,29 +97,43 @@ func (clients ClientNameMap) Remove(client *Client) error {
 
 type ChannelModeSet map[ChannelMode]bool
 
-type ClientSet map[*Client]ChannelModeSet
+type ClientSet map[*Client]bool
 
 func (clients ClientSet) Add(client *Client) {
-	clients[client] = make(ChannelModeSet)
+	clients[client] = true
 }
 
 func (clients ClientSet) Remove(client *Client) {
 	delete(clients, client)
 }
 
-func (clients ClientSet) HasMode(client *Client, mode ChannelMode) bool {
-	modes, ok := clients[client]
+func (clients ClientSet) Has(client *Client) bool {
+	return clients[client]
+}
+
+type MemberSet map[*Client]ChannelModeSet
+
+func (members MemberSet) Add(member *Client) {
+	members[member] = make(ChannelModeSet)
+}
+
+func (members MemberSet) Remove(member *Client) {
+	delete(members, member)
+}
+
+func (members MemberSet) Has(member *Client) bool {
+	_, ok := members[member]
+	return ok
+}
+
+func (members MemberSet) HasMode(member *Client, mode ChannelMode) bool {
+	modes, ok := members[member]
 	if !ok {
 		return false
 	}
 	return modes[mode]
 }
 
-func (clients ClientSet) Has(client *Client) bool {
-	_, ok := clients[client]
-	return ok
-}
-
 type ChannelSet map[*Channel]bool
 
 func (channels ChannelSet) Add(channel *Channel) {
@@ -141,6 +165,7 @@ type Replier interface {
 }
 
 type Reply interface {
+	Code() ReplyCode
 	Format(*Client) []string
 	Source() Identifier
 }
@@ -172,6 +197,10 @@ type ChannelCommand interface {
 	HandleChannel(channel *Channel)
 }
 
+type ClientCommand interface {
+	HandleClient(client *Client)
+}
+
 //
 // structs
 //