diff --git a/irc/commands.go b/irc/commands.go
index c9a4550c..22153041 100644
--- a/irc/commands.go
+++ b/irc/commands.go
@@ -966,7 +966,7 @@ func NewTheaterCommand(args []string) (Command, error) {
 		return &TheaterActionCommand{
 			channel: NewName(args[1]),
 			asNick:  NewName(args[2]),
-			action:  NewText(args[3]),
+			action:  NewCTCPText(args[3]),
 		}, nil
 	} else {
 		return nil, ErrParseCommand
diff --git a/irc/reply.go b/irc/reply.go
index 040aedbf..2c11bea2 100644
--- a/irc/reply.go
+++ b/irc/reply.go
@@ -99,6 +99,10 @@ func RplPrivMsg(source Identifiable, target Identifiable, message Text) string {
 	return NewStringReply(source, PRIVMSG, "%s :%s", target.Nick(), message)
 }
 
+func RplCTCPAction(source Identifiable, target Identifiable, action CTCPText) string {
+	return RplPrivMsg(source, target, NewText(fmt.Sprintf("\x01ACTION %s\x01", action)))
+}
+
 func RplNotice(source Identifiable, target Identifiable, message Text) string {
 	return NewStringReply(source, NOTICE, "%s :%s", target.Nick(), message)
 }
diff --git a/irc/strings.go b/irc/strings.go
index dfd01fcb..b8cc9227 100644
--- a/irc/strings.go
+++ b/irc/strings.go
@@ -64,3 +64,12 @@ func NewText(str string) Text {
 func (text Text) String() string {
 	return string(text)
 }
+
+// CTCPText is text suitable escaped for CTCP.
+type CTCPText string
+
+var ctcpEscaper = strings.NewReplacer("\x00", "\x200", "\n", "\x20n", "\r", "\x20r")
+
+func NewCTCPText(str string) CTCPText {
+	return CTCPText(ctcpEscaper.Replace(str))
+}
diff --git a/irc/theater.go b/irc/theater.go
index 783c851b..36525048 100644
--- a/irc/theater.go
+++ b/irc/theater.go
@@ -51,9 +51,12 @@ func (m *TheaterIdentifyCommand) HandleServer(s *Server) {
 		return
 	}
 
-	if !channel.members.AnyHasMode(Theater) {
-		channel.members[client][Theater] = true
+	if channel.members.AnyHasMode(Theater) {
+		client.Reply(RplNotice(s, client, "someone else is +T in this channel"))
+		return
 	}
+
+	channel.members[client][Theater] = true
 }
 
 type TheaterPrivMsgCommand struct {
@@ -69,6 +72,7 @@ func (cmd *TheaterPrivMsgCommand) String() string {
 }
 func (m *TheaterPrivMsgCommand) HandleServer(s *Server) {
 	client := m.Client()
+
 	if !m.channel.IsChannel() {
 		client.ErrNoSuchChannel(m.channel)
 		return
@@ -80,10 +84,13 @@ func (m *TheaterPrivMsgCommand) HandleServer(s *Server) {
 		return
 	}
 
-	if channel.members.HasMode(client, Theater) {
-		for member := range channel.members {
-			member.Reply(RplPrivMsg(TheaterClient(m.asNick), channel, m.message))
-		}
+	if !channel.members.HasMode(client, Theater) {
+		client.Reply(RplNotice(s, client, "you are not +T"))
+		return
+	}
+
+	for member := range channel.members {
+		member.Reply(RplPrivMsg(TheaterClient(m.asNick), channel, m.message))
 	}
 }
 
@@ -91,7 +98,7 @@ type TheaterActionCommand struct {
 	BaseCommand
 	channel Name
 	asNick  Name
-	action  Text
+	action  CTCPText
 }
 
 func (cmd *TheaterActionCommand) String() string {
@@ -100,7 +107,8 @@ func (cmd *TheaterActionCommand) String() string {
 
 func (m *TheaterActionCommand) HandleServer(s *Server) {
 	client := m.Client()
-	if m.channel.IsChannel() {
+
+	if !m.channel.IsChannel() {
 		client.ErrNoSuchChannel(m.channel)
 		return
 	}
@@ -111,9 +119,12 @@ func (m *TheaterActionCommand) HandleServer(s *Server) {
 		return
 	}
 
-	if channel.members.HasMode(client, Theater) {
-		for member := range channel.members {
-			member.Reply(RplPrivMsg(TheaterClient(m.asNick), channel, NewText(fmt.Sprintf("\001ACTION %s\001", m.action))))
-		}
+	if !channel.members.HasMode(client, Theater) {
+		client.Reply(RplNotice(s, client, "you are not +T"))
+		return
+	}
+
+	for member := range channel.members {
+		member.Reply(RplCTCPAction(TheaterClient(m.asNick), channel, m.action))
 	}
 }
diff --git a/irc/types.go b/irc/types.go
index db698254..dabe4c2b 100644
--- a/irc/types.go
+++ b/irc/types.go
@@ -85,7 +85,7 @@ func (members MemberSet) HasMode(member *Client, mode ChannelMode) bool {
 
 func (members MemberSet) AnyHasMode(mode ChannelMode) bool {
 	for _, modes := range members {
-		if modes[Theater] {
+		if modes[mode] {
 			return true
 		}
 	}