diff --git a/arp/handler.go b/arp/handler.go
index 4ba5a86..45748bf 100644
--- a/arp/handler.go
+++ b/arp/handler.go
@@ -255,7 +255,7 @@ func (h *Handler) Demux(ethFrame []byte, frameOffset int) error {
 }
 
 func trySetEthernetDst(ethFrame []byte, dst []byte) {
-	if len(ethFrame) > 14 {
+	if len(ethFrame) >= 14 {
 		copy(ethFrame[:6], dst)
 	}
 }
diff --git a/x/xnet/stack-async.go b/x/xnet/stack-async.go
index 9a3c5b6..6be8eaa 100644
--- a/x/xnet/stack-async.go
+++ b/x/xnet/stack-async.go
@@ -28,7 +28,7 @@ type StackAsync struct {
 	ip       internet.StackIP
 	arp      arp.Handler
 	udps     internet.StackPorts
-	tcps     internet.StackPorts
+	tcps     internet.StackPortsMACFiltered
 
 	dhcpUDP     internet.StackUDPPort
 	dhcp        dhcpv4.Client
@@ -250,7 +250,7 @@ func (s *StackAsync) DialTCP(conn *tcp.Conn, localPort uint16, addrp netip.AddrP
 	if err != nil {
 		return err
 	}
-	err = s.tcps.Register(conn) // MAC is set later on by ARP response arriving to our network.
+	err = s.tcps.Register(conn, mac) // MAC is set later on by ARP response arriving to our network.
 	if err != nil {
 		conn.Abort()
 		return err
@@ -265,7 +265,7 @@ func (s *StackAsync) ListenTCP(conn *tcp.Conn, localPort uint16) (err error) {
 	if err != nil {
 		return err
 	}
-	err = s.tcps.Register(conn)
+	err = s.tcps.Register(conn, nil)
 	if err != nil {
 		conn.Abort()
 		return err