diff --git a/group/group.go b/group/group.go
index 82e6c39..2e8b31c 100644
--- a/group/group.go
+++ b/group/group.go
@@ -701,8 +701,12 @@ func kickall(g *Group, message string) {
 	})
 }
 
-func (g *Group) Shutdown(message string) {
-	kickall(g, message)
+func Shutdown(message string) {
+	Range(func(g *Group) bool {
+		g.SetLocked(true, message)
+		kickall(g, message)
+		return true
+	})
 }
 
 type warner interface {
diff --git a/webserver/webserver.go b/webserver/webserver.go
index 3fdffce..e43a79a 100644
--- a/webserver/webserver.go
+++ b/webserver/webserver.go
@@ -70,10 +70,7 @@ func Serve(address string, dataDir string) error {
 		}
 	}
 	s.RegisterOnShutdown(func() {
-		group.Range(func(g *group.Group) bool {
-			go g.Shutdown("server is shutting down")
-			return true
-		})
+		group.Shutdown("server is shutting down")
 	})
 
 	server.Store(s)