diff --git a/common/urltest/urltest.go b/common/urltest/urltest.go
index bfeb13ba3d..7b5378dbc5 100644
--- a/common/urltest/urltest.go
+++ b/common/urltest/urltest.go
@@ -8,7 +8,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/imkira/go-observer"
+	"github.com/imkira/go-observer/v2"
 	"github.com/sagernet/sing/common"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
@@ -22,7 +22,7 @@ type History struct {
 type HistoryStorage struct {
 	access       sync.RWMutex
 	delayHistory map[string]*History
-	updateHook   observer.Property
+	updateHook   observer.Property[int]
 }
 
 func NewHistoryStorage() *HistoryStorage {
@@ -31,7 +31,7 @@ func NewHistoryStorage() *HistoryStorage {
 	}
 }
 
-func (s *HistoryStorage) SetHook(hook observer.Property) {
+func (s *HistoryStorage) SetHook(hook observer.Property[int]) {
 	s.updateHook = hook
 }
 
diff --git a/experimental/libbox/command_group.go b/experimental/libbox/command_group.go
index 191fb8dc99..35aebe9fe4 100644
--- a/experimental/libbox/command_group.go
+++ b/experimental/libbox/command_group.go
@@ -91,6 +91,7 @@ func (s *CommandServer) handleGroupConn(conn net.Conn, onlyGroupItems bool) erro
 		case <-ctx.Done():
 			return ctx.Err()
 		case <-urlTestUpdateStream.Changes():
+			urlTestUpdateStream.Next()
 		}
 	}
 }
diff --git a/experimental/libbox/command_server.go b/experimental/libbox/command_server.go
index 430613ddb3..cab1da5b5a 100644
--- a/experimental/libbox/command_server.go
+++ b/experimental/libbox/command_server.go
@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 	"sync"
 
-	"github.com/imkira/go-observer"
+	"github.com/imkira/go-observer/v2"
 	"github.com/sagernet/sing-box/common/urltest"
 	"github.com/sagernet/sing-box/experimental/clashapi"
 	"github.com/sagernet/sing-box/log"
@@ -31,7 +31,7 @@ type CommandServer struct {
 	service    *BoxService
 
 	// These channels only work with a single client. if multi-client support is needed, replace with Subscriber/Observer
-	urlTestUpdate observer.Property
+	urlTestUpdate observer.Property[int]
 	modeUpdate    chan struct{}
 	logReset      chan struct{}
 }