diff --git a/br/pkg/task/stream.go b/br/pkg/task/stream.go
index 3683854dc2169..d3957d54d277e 100644
--- a/br/pkg/task/stream.go
+++ b/br/pkg/task/stream.go
@@ -135,7 +135,8 @@ func DefineStreamStartFlags(flags *pflag.FlagSet) {
 	flags.String(flagStreamStartTS, "",
 		"usually equals last full backupTS, used for backup log. Default value is current ts.\n"+
 			"support TSO or datetime, e.g. '400036290571534337' or '2018-05-11 01:42:23'.")
-	flags.String(flagStreamEndTS, "2035-1-1 00:00:00", "end ts, indicate stopping observe after endTS"+
+	// 999999999999999999 means 2090-11-18 22:07:45
+	flags.String(flagStreamEndTS, "999999999999999999", "end ts, indicate stopping observe after endTS"+
 		"support TSO or datetime")
 	_ = flags.MarkHidden(flagStreamEndTS)
 	flags.Int64(flagGCSafePointTTS, utils.DefaultStreamStartSafePointTTL,