diff --git a/irc/getters.go b/irc/getters.go
index f4b86391..6031659f 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -4,6 +4,7 @@
 package irc
 
 import (
+	"fmt"
 	"net"
 	"sync/atomic"
 	"time"
@@ -493,7 +494,7 @@ func (client *Client) GetReadMarker(cfname string) (result string) {
 	t, ok := client.readMarkers[cfname]
 	client.stateMutex.RUnlock()
 	if ok {
-		return t.Format(IRCv3TimestampFormat)
+		return fmt.Sprintf("timestamp=%s", t.Format(IRCv3TimestampFormat))
 	}
 	return "*"
 }
diff --git a/irc/handlers.go b/irc/handlers.go
index 75f2d54f..43cd00f8 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2770,14 +2770,14 @@ func markReadHandler(server *Server, client *Client, msg ircmsg.Message, rb *Res
 	}
 
 	// "MARKREAD client set command": MARKREAD <target> <timestamp>
-	readTimestamp := msg.Params[1]
+	readTimestamp := strings.TrimPrefix(msg.Params[1], "timestamp=")
 	readTime, err := time.Parse(IRCv3TimestampFormat, readTimestamp)
 	if err != nil {
 		rb.Add(nil, server.name, "FAIL", "MARKREAD", "INVALID_PARAMS", utils.SafeErrorParam(readTimestamp), client.t("Invalid timestamp"))
 		return
 	}
 	result := client.SetReadMarker(cftarget, readTime)
-	readTimestamp = result.Format(IRCv3TimestampFormat)
+	readTimestamp = fmt.Sprintf("timestamp=%s", result.Format(IRCv3TimestampFormat))
 	// inform the originating session whether it was a success or a no-op:
 	rb.Add(nil, server.name, "MARKREAD", unfoldedTarget, readTimestamp)
 	if result.Equal(readTime) {