diff --git a/src/device.c b/src/device.c
index 88790d6..42ded33 100644
--- a/src/device.c
+++ b/src/device.c
@@ -119,6 +119,7 @@ static netdev_tx_t xmit(struct sk_buff *skb, struct net_device *dev)
 	struct wireguard_peer *peer;
 	struct sk_buff *next;
 	struct sk_buff_head packets;
+	struct dst_entry *dst;
 	sa_family_t family;
 	u32 mtu;
 	int ret;
@@ -143,7 +144,8 @@ static netdev_tx_t xmit(struct sk_buff *skb, struct net_device *dev)
 		goto err_peer;
 	}
 
-	mtu = dst_mtu(skb_dst(skb));
+	dst = skb_dst(skb);
+	mtu = dst ? dst_mtu(dst) : dev->mtu;
 
 	__skb_queue_head_init(&packets);
 	if (!skb_is_gso(skb))