diff --git a/sys/net/if_epair.c b/sys/net/if_epair.c
--- a/sys/net/if_epair.c
+++ b/sys/net/if_epair.c
@@ -629,6 +629,7 @@
 	ifp->if_dname = epairname;
 	ifp->if_dunit = unit;
 	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
+	ifp->if_flags |= IFF_KNOWSEPOCH;
 	ifp->if_capabilities = IFCAP_VLAN_MTU;
 	ifp->if_capenable = IFCAP_VLAN_MTU;
 	ifp->if_start = epair_start;