diff --git a/bridge/mattermost/mattermost.go b/bridge/mattermost/mattermost.go
index 42843d00..51d32424 100644
--- a/bridge/mattermost/mattermost.go
+++ b/bridge/mattermost/mattermost.go
@@ -8,12 +8,14 @@ import (
 	"github.com/42wim/matterbridge/bridge/helper"
 	"github.com/42wim/matterbridge/matterclient"
 	"github.com/42wim/matterbridge/matterhook"
+	"github.com/rs/xid"
 	"strings"
 )
 
 type Bmattermost struct {
 	mh     *matterhook.Client
 	mc     *matterclient.MMClient
+	uuid   string
 	TeamID string
 	*bridge.Config
 	avatarMap map[string]string
@@ -21,6 +23,7 @@ type Bmattermost struct {
 
 func New(cfg *bridge.Config) bridge.Bridger {
 	b := &Bmattermost{Config: cfg, avatarMap: make(map[string]string)}
+	b.uuid = xid.New().String()
 	return b
 }
 
@@ -366,7 +369,7 @@ func (b *Bmattermost) sendWebhook(msg config.Message) (string, error) {
 		// this sends a message only if we received a config.EVENT_FILE_FAILURE_SIZE
 		for _, rmsg := range helper.HandleExtra(&msg, b.General) {
 			matterMessage := matterhook.OMessage{IconURL: b.GetString("IconURL"), Channel: rmsg.Channel, UserName: rmsg.Username, Text: rmsg.Text, Props: make(map[string]interface{})}
-			matterMessage.Props["matterbridge_"+b.mc.User.Id] = true
+			matterMessage.Props["matterbridge_"+b.uuid] = true
 			b.mh.Send(matterMessage)
 		}
 
@@ -385,7 +388,7 @@ func (b *Bmattermost) sendWebhook(msg config.Message) (string, error) {
 	if msg.Avatar != "" {
 		matterMessage.IconURL = msg.Avatar
 	}
-	matterMessage.Props["matterbridge_"+b.mc.User.Id] = true
+	matterMessage.Props["matterbridge_"+b.uuid] = true
 	err := b.mh.Send(matterMessage)
 	if err != nil {
 		b.Log.Info(err)
@@ -415,7 +418,7 @@ func (b *Bmattermost) skipMessage(message *matterclient.Message) bool {
 
 	// Ignore messages sent from matterbridge
 	if message.Post.Props != nil {
-		if _, ok := message.Post.Props["matterbridge_"+b.mc.User.Id].(bool); ok {
+		if _, ok := message.Post.Props["matterbridge_"+b.uuid].(bool); ok {
 			b.Log.Debugf("sent by matterbridge, ignoring")
 			return true
 		}
diff --git a/bridge/slack/slack.go b/bridge/slack/slack.go
index cedb18e7..1633d820 100644
--- a/bridge/slack/slack.go
+++ b/bridge/slack/slack.go
@@ -15,6 +15,7 @@ import (
 	"github.com/42wim/matterbridge/bridge/helper"
 	"github.com/42wim/matterbridge/matterhook"
 	"github.com/nlopes/slack"
+	"github.com/rs/xid"
 )
 
 type Bslack struct {
@@ -25,6 +26,7 @@ type Bslack struct {
 	Usergroups []slack.UserGroup
 	si         *slack.Info
 	channels   []slack.Channel
+	uuid       string
 	*bridge.Config
 	sync.RWMutex
 }
@@ -32,7 +34,7 @@ type Bslack struct {
 const messageDeleted = "message_deleted"
 
 func New(cfg *bridge.Config) bridge.Bridger {
-	return &Bslack{Config: cfg}
+	return &Bslack{Config: cfg, uuid: xid.New().String()}
 }
 
 func (b *Bslack) Command(cmd string) string {
@@ -177,7 +179,7 @@ func (b *Bslack) Send(msg config.Message) (string, error) {
 		np.IconURL = msg.Avatar
 	}
 	// add a callback ID so we can see we created it
-	np.Attachments = append(np.Attachments, slack.Attachment{CallbackID: "matterbridge_" + b.si.User.ID})
+	np.Attachments = append(np.Attachments, slack.Attachment{CallbackID: "matterbridge_" + b.uuid})
 	// add file attachments
 	np.Attachments = append(np.Attachments, b.createAttach(msg.Extra)...)
 	// add slack attachments (from another slack bridge)
@@ -657,7 +659,7 @@ func (b *Bslack) skipMessageEvent(ev *slack.MessageEvent) bool {
 
 	// skip messages we made ourselves
 	if len(ev.Attachments) > 0 {
-		if ev.Attachments[0].CallbackID == "matterbridge_"+b.si.User.ID {
+		if ev.Attachments[0].CallbackID == "matterbridge_"+b.uuid {
 			return true
 		}
 	}