Index: if_trunk.c
===================================================================
RCS file: /cvs/src/sys/net/if_trunk.c,v
retrieving revision 1.143
diff -u -p -r1.143 if_trunk.c
--- if_trunk.c	7 Nov 2019 07:36:32 -0000	1.143
+++ if_trunk.c	5 Dec 2019 10:23:47 -0000
@@ -310,7 +310,7 @@ trunk_port_create(struct trunk_softc *tr
 			printf("%s: first port, setting trunk mtu %u\n",
 			    tr->tr_ifname, ifp->if_mtu);
 		tr->tr_ac.ac_if.if_mtu = ifp->if_mtu;
-		tr->tr_ac.ac_if.if_hardmtu = ifp->if_mtu;
+		tr->tr_ac.ac_if.if_hardmtu = ifp->if_hardmtu;
 	} else if (tr->tr_ac.ac_if.if_mtu != ifp->if_mtu) {
 		printf("%s: adding %s failed, MTU %u != %u\n", tr->tr_ifname,
 		    ifp->if_xname, ifp->if_mtu, tr->tr_ac.ac_if.if_mtu);