diff --git a/sys/net/if_vxlan.c b/sys/net/if_vxlan.c
--- a/sys/net/if_vxlan.c
+++ b/sys/net/if_vxlan.c
@@ -1627,6 +1627,8 @@
 		ifp->if_hdrlen += sizeof(struct ip);
 	else if (VXLAN_SOCKADDR_IS_IPV6(&sc->vxl_dst_addr) != 0)
 		ifp->if_hdrlen += sizeof(struct ip6_hdr);
+
+	ifp->if_mtu -= ifp->if_hdrlen;
 }
 
 static int