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
@@ -133,6 +133,8 @@
 static void
 epair_clear_mbuf(struct mbuf *m)
 {
+	M_ASSERTPKTHDR(m);
+
 	/* Remove any CSUM_SND_TAG as ether_input will barf. */
 	if (m->m_pkthdr.csum_flags & CSUM_SND_TAG) {
 		m_snd_tag_rele(m->m_pkthdr.snd_tag);
@@ -140,6 +142,10 @@
 		m->m_pkthdr.csum_flags &= ~CSUM_SND_TAG;
 	}
 
+	/* Clear vlan information. */
+	m->m_flags &= ~M_VLANTAG;
+	m->m_pkthdr.ether_vtag = 0;
+
 	m_tag_delete_nonpersistent(m);
 }