diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 9a2f8e41a26ee9684fdea46adf684e9e88727ed9..87e48a4e105133ca3d0407b5c2d84f1b0e3a72c4 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -179,6 +179,7 @@ int qdisc_restart(struct net_device *dev)
 		netif_schedule(dev);
 		return 1;
 	}
+	BUG_ON((int) q->q.qlen < 0);
 	return q->q.qlen;
 }