diff --git a/irc/modes/modes.go b/irc/modes/modes.go
index 9e311298..ae2d9224 100644
--- a/irc/modes/modes.go
+++ b/irc/modes/modes.go
@@ -6,6 +6,7 @@
 package modes
 
 import (
+	"sort"
 	"strings"
 
 	"github.com/oragono/oragono/irc/utils"
@@ -418,3 +419,27 @@ func (set *ModeSet) HighestChannelUserMode() (result Mode) {
 	}
 	return
 }
+
+type ByCodepoint Modes
+
+func (a ByCodepoint) Len() int           { return len(a) }
+func (a ByCodepoint) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a ByCodepoint) Less(i, j int) bool { return a[i] < a[j] }
+
+func RplMyInfo() (param1, param2, param3 string) {
+	userModes := make(Modes, len(SupportedUserModes))
+	copy(userModes, SupportedUserModes)
+	sort.Sort(ByCodepoint(userModes))
+
+	channelModes := make(Modes, len(SupportedChannelModes)+len(ChannelUserModes))
+	copy(channelModes, SupportedChannelModes)
+	copy(channelModes[len(SupportedChannelModes):], ChannelUserModes)
+	sort.Sort(ByCodepoint(channelModes))
+
+	// XXX enumerate these by hand, i can't see any way to DRY this
+	channelParametrizedModes := Modes{BanMask, ExceptMask, InviteMask, Key, UserLimit}
+	channelParametrizedModes = append(channelParametrizedModes, ChannelUserModes...)
+	sort.Sort(ByCodepoint(channelParametrizedModes))
+
+	return userModes.String(), channelModes.String(), channelParametrizedModes.String()
+}
diff --git a/irc/server.go b/irc/server.go
index dfeb118a..d20ebd35 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -36,10 +36,8 @@ var (
 	// common error line to sub values into
 	errorMsg = "ERROR :%s\r\n"
 
-	// supportedUserModesString acts as a cache for when we introduce users
-	supportedUserModesString = modes.SupportedUserModes.String()
-	// supportedChannelModesString acts as a cache for when we introduce users
-	supportedChannelModesString = modes.SupportedChannelModes.String()
+	// three final parameters of 004 RPL_MYINFO, enumerating our supported modes
+	rplMyInfo1, rplMyInfo2, rplMyInfo3 = modes.RplMyInfo()
 
 	// whitelist of caps to serve on the STS-only listener. In particular,
 	// never advertise SASL, to discourage people from sending their passwords:
@@ -297,8 +295,7 @@ func (server *Server) playRegistrationBurst(session *Session) {
 	session.Send(nil, server.name, RPL_WELCOME, d.nick, fmt.Sprintf(c.t("Welcome to the Internet Relay Network %s"), d.nick))
 	session.Send(nil, server.name, RPL_YOURHOST, d.nick, fmt.Sprintf(c.t("Your host is %[1]s, running version %[2]s"), server.name, Ver))
 	session.Send(nil, server.name, RPL_CREATED, d.nick, fmt.Sprintf(c.t("This server was created %s"), server.ctime.Format(time.RFC1123)))
-	//TODO(dan): Look at adding last optional [<channel modes with a parameter>] parameter
-	session.Send(nil, server.name, RPL_MYINFO, d.nick, server.name, Ver, supportedUserModesString, supportedChannelModesString)
+	session.Send(nil, server.name, RPL_MYINFO, d.nick, server.name, Ver, rplMyInfo1, rplMyInfo2, rplMyInfo3)
 
 	if c.isSTSOnly {
 		for _, line := range server.Config().Server.STS.bannerLines {