diff --git a/src/netif/ppp/pppos.c b/src/netif/ppp/pppos.c
index 7bf40f21..e0f0d26f 100644
--- a/src/netif/ppp/pppos.c
+++ b/src/netif/ppp/pppos.c
@@ -217,6 +217,9 @@ pppos_write(ppp_pcb *ppp, void *ctx, struct pbuf *p)
     return ERR_MEM;
   }
 
+  /* Set nb->tot_len to actual payload length */
+  nb->tot_len = p->len;
+
   /* If the link has been idle, we'll send a fresh flag character to
    * flush any noise. */
   err = ERR_OK;
@@ -262,6 +265,9 @@ pppos_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *pb, u16_t protocol)
     return ERR_MEM;
   }
 
+  /* Set nb->tot_len to actual payload length */
+  nb->tot_len = pb->tot_len;
+
   /* If the link has been idle, we'll send a fresh flag character to
    * flush any noise. */
   err = ERR_OK;