diff --git a/sys/net/dummynet3/ip_dummynet3.c b/sys/net/dummynet3/ip_dummynet3.c
--- a/sys/net/dummynet3/ip_dummynet3.c
+++ b/sys/net/dummynet3/ip_dummynet3.c
@@ -448,7 +448,7 @@
  * either a pipe (WF2Q) or a flow_queue (per-flow queueing)
  */
 #define SET_TICKS(pkt, q, p)	\
-	(pkt->dn_m->m_pkthdr.len*8*dn_hz - (q)->numbytes + p->bandwidth - 1 ) / \
+	((int64_t)(pkt)->dn_m->m_pkthdr.len*8*(int64_t)dn_hz - (q)->numbytes + p->bandwidth - 1 ) /\
 		p->bandwidth;
 
 /*