diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1440,6 +1440,10 @@
 			if_printf(ife, "unable to prepend 802.1Q header");
 			return (false);
 		}
+		if ((*mp)->m_flags & M_VLANTAG) {
+			(*mp)->m_flags &= ~M_VLANTAG;
+			(*mp)->m_pkthdr.ether_vtag = 0;
+		}
 	}
 	return (true);
 }