diff --git a/sys/netinet/in_mcast.c b/sys/netinet/in_mcast.c
--- a/sys/netinet/in_mcast.c
+++ b/sys/netinet/in_mcast.c
@@ -263,6 +263,7 @@
 	if_ref(ifp);
 	if (ifma->ifma_flags & IFMA_F_ENQUEUED) {
 		CK_STAILQ_REMOVE(&ifp->if_multiaddrs, ifma, ifmultiaddr, ifma_link);
+		mbufq_drain(&inm->inm_scq);
 		ifma->ifma_flags &= ~IFMA_F_ENQUEUED;
 	}
 	MCDPRINTF("removed ifma: %p from %s\n", ifma, ifp->if_xname);