diff --git a/drivers/net/mmnif.c b/drivers/net/mmnif.c
index 0417550b..1b70889f 100644
--- a/drivers/net/mmnif.c
+++ b/drivers/net/mmnif.c
@@ -755,6 +755,8 @@ err_t mmnif_tx(struct netif* netif, struct pbuf* p)
 	else
 		mmnif_write_rx_buffl(dest_ip, pos, p->payload,p->tot_len);
 
+	sleep(1);
+
 	/* like above ensure we are the only ones editing the hdr */
 	mmnif_lock_rx_hdr(dest_ip);