diff --git a/gold/link/peer.go b/gold/link/peer.go
index e48a97d..6c1a319 100644
--- a/gold/link/peer.go
+++ b/gold/link/peer.go
@@ -28,7 +28,7 @@ func (m *Me) AddPeer(cfg *PeerConfig) (l *Link) {
 	if ok {
 		return
 	}
-	if cfg.MTU == 0 || cfg.MTU == 65535 || cfg.MTU > m.mtu {
+	if cfg.MTU == 0 || cfg.MTU == 65535 || (m.mtu != 0 && cfg.MTU > m.mtu) {
 		panic("invalid mtu for peer " + cfg.PeerIP)
 	}
 	l = &Link{
diff --git a/upper/services/wg/wg.go b/upper/services/wg/wg.go
index e2bc0a8..ca97302 100644
--- a/upper/services/wg/wg.go
+++ b/upper/services/wg/wg.go
@@ -93,7 +93,7 @@ func (wg *WG) init(srcport, dstport uint16) {
 		MyIPwithMask: wg.c.IP + "/32",
 		MyEndpoint:   wg.c.EndPoint,
 		PrivateKey:   &wg.key,
-		NIC:          lower.NewNIC(wg.c.IP, wg.c.SubNet, strconv.FormatInt(wg.c.MTU, 64), cidrs...),
+		NIC:          lower.NewNIC(wg.c.IP, wg.c.SubNet, strconv.FormatInt(wg.c.MTU, 10), cidrs...),
 		SrcPort:      srcport,
 		DstPort:      dstport,
 		MTU:          uint16(wg.c.MTU),