diff --git a/irc/client.go b/irc/client.go
index 5cf9a476..4e076b54 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -227,6 +227,10 @@ func (client *Client) Friends() ClientSet {
 }
 
 func (client *Client) SetNickname(nickname Name) {
+	if client.HasNick() {
+		Log.error.Printf("%s nickname already set!", client)
+		return
+	}
 	client.nick = nickname
 	client.server.clients.Add(client)
 }
diff --git a/irc/commands.go b/irc/commands.go
index 7601969b..6c2e053a 100644
--- a/irc/commands.go
+++ b/irc/commands.go
@@ -40,6 +40,7 @@ var (
 		NAMES:   NewNamesCommand,
 		NICK:    NewNickCommand,
 		NOTICE:  NewNoticeCommand,
+		ONICK:   NewOperNickCommand,
 		OPER:    NewOperCommand,
 		PART:    NewPartCommand,
 		PASS:    NewPassCommand,
@@ -228,15 +229,6 @@ func NewPassCommand(args []string) (Command, error) {
 
 // NICK <nickname>
 
-type NickCommand struct {
-	BaseCommand
-	nickname Name
-}
-
-func (m *NickCommand) String() string {
-	return fmt.Sprintf("NICK(nickname=%s)", m.nickname)
-}
-
 func NewNickCommand(args []string) (Command, error) {
 	if len(args) != 1 {
 		return nil, NotEnoughArgsError
@@ -1006,3 +998,14 @@ func NewWhoWasCommand(args []string) (Command, error) {
 	}
 	return cmd, nil
 }
+
+func NewOperNickCommand(args []string) (Command, error) {
+	if len(args) < 2 {
+		return nil, NotEnoughArgsError
+	}
+
+	return &OperNickCommand{
+		target: NewName(args[0]),
+		nick:   NewName(args[1]),
+	}, nil
+}
diff --git a/irc/constants.go b/irc/constants.go
index d9426cb8..0fc6b0d1 100644
--- a/irc/constants.go
+++ b/irc/constants.go
@@ -21,6 +21,7 @@ const (
 	NAMES   StringCode = "NAMES"
 	NICK    StringCode = "NICK"
 	NOTICE  StringCode = "NOTICE"
+	ONICK   StringCode = "ONICK"
 	OPER    StringCode = "OPER"
 	PART    StringCode = "PART"
 	PASS    StringCode = "PASS"
diff --git a/irc/nickname.go b/irc/nickname.go
new file mode 100644
index 00000000..00a27c17
--- /dev/null
+++ b/irc/nickname.go
@@ -0,0 +1,99 @@
+package irc
+
+import (
+	"fmt"
+)
+
+type NickCommand struct {
+	BaseCommand
+	nickname Name
+}
+
+func (m *NickCommand) String() string {
+	return fmt.Sprintf("NICK(nickname=%s)", m.nickname)
+}
+
+func (m *NickCommand) HandleRegServer(s *Server) {
+	client := m.Client()
+	if !client.authorized {
+		client.ErrPasswdMismatch()
+		client.Quit("bad password")
+		return
+	}
+
+	if client.capState == CapNegotiating {
+		client.capState = CapNegotiated
+	}
+
+	if m.nickname == "" {
+		client.ErrNoNicknameGiven()
+		return
+	}
+
+	if s.clients.Get(m.nickname) != nil {
+		client.ErrNickNameInUse(m.nickname)
+		return
+	}
+
+	if !m.nickname.IsNickname() {
+		client.ErrErroneusNickname(m.nickname)
+		return
+	}
+
+	client.SetNickname(m.nickname)
+	s.tryRegister(client)
+}
+
+func (msg *NickCommand) HandleServer(server *Server) {
+	client := msg.Client()
+
+	if msg.nickname == "" {
+		client.ErrNoNicknameGiven()
+		return
+	}
+
+	if !msg.nickname.IsNickname() {
+		client.ErrErroneusNickname(msg.nickname)
+		return
+	}
+
+	if msg.nickname == client.nick {
+		return
+	}
+
+	target := server.clients.Get(msg.nickname)
+	if (target != nil) && (target != client) {
+		client.ErrNickNameInUse(msg.nickname)
+		return
+	}
+
+	client.ChangeNickname(msg.nickname)
+}
+
+type OperNickCommand struct {
+	BaseCommand
+	target Name
+	nick   Name
+}
+
+func (msg *OperNickCommand) HandleServer(server *Server) {
+	client := msg.Client()
+
+	if !client.flags[Operator] {
+		client.ErrNoPrivileges()
+		return
+	}
+
+	if !msg.nick.IsNickname() {
+		client.ErrErroneusNickname(msg.nick)
+		return
+	}
+
+	target := server.clients.Get(msg.target)
+	if target == nil {
+		client.ErrNoSuchNick(msg.target)
+		return
+	}
+
+	target.ChangeNickname(msg.nick)
+}
diff --git a/irc/server.go b/irc/server.go
index c6ccc7c4..927d9b31 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -289,37 +289,6 @@ func (msg *ProxyCommand) HandleRegServer(server *Server) {
 	msg.Client().hostname = msg.hostname
 }
 
-func (m *NickCommand) HandleRegServer(s *Server) {
-	client := m.Client()
-	if !client.authorized {
-		client.ErrPasswdMismatch()
-		client.Quit("bad password")
-		return
-	}
-
-	if client.capState == CapNegotiating {
-		client.capState = CapNegotiated
-	}
-
-	if m.nickname == "" {
-		client.ErrNoNicknameGiven()
-		return
-	}
-
-	if s.clients.Get(m.nickname) != nil {
-		client.ErrNickNameInUse(m.nickname)
-		return
-	}
-
-	if !m.nickname.IsNickname() {
-		client.ErrErroneusNickname(m.nickname)
-		return
-	}
-
-	client.SetNickname(m.nickname)
-	s.tryRegister(client)
-}
-
 func (msg *RFC1459UserCommand) HandleRegServer(server *Server) {
 	client := msg.Client()
 	if !client.authorized {
@@ -380,32 +349,6 @@ func (m *PongCommand) HandleServer(s *Server) {
 	// no-op
 }
 
-func (msg *NickCommand) HandleServer(server *Server) {
-	client := msg.Client()
-
-	if msg.nickname == "" {
-		client.ErrNoNicknameGiven()
-		return
-	}
-
-	if !msg.nickname.IsNickname() {
-		client.ErrErroneusNickname(msg.nickname)
-		return
-	}
-
-	if msg.nickname == client.nick {
-		return
-	}
-
-	target := server.clients.Get(msg.nickname)
-	if (target != nil) && (target != client) {
-		client.ErrNickNameInUse(msg.nickname)
-		return
-	}
-
-	client.ChangeNickname(msg.nickname)
-}
-
 func (m *UserCommand) HandleServer(s *Server) {
 	m.Client().ErrAlreadyRegistered()
 }