diff --git a/src/netif/ppp/pppos.c b/src/netif/ppp/pppos.c
index c4a0bd09..88a4503a 100644
--- a/src/netif/ppp/pppos.c
+++ b/src/netif/ppp/pppos.c
@@ -207,10 +207,9 @@ pppos_write(ppp_pcb *ppp, void *ctx, struct pbuf *p)
   err_t err;
   LWIP_UNUSED_ARG(ppp);
 
-  /* Grab an output buffer. Using PBUF_POOL here for tx is ok since the pbuf
-     gets freed by 'pppos_output_last' before this function returns and thus
-     cannot starve rx. */
-  nb = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);
+  /* Grab an output buffer. Assume PBUF_POOL_BUFSIZE is an acceptable
+   * chunk size for Tx as well. */
+  nb = pbuf_alloc(PBUF_RAW, PBUF_POOL_BUFSIZE, PBUF_RAM);
   if (nb == NULL) {
     PPPDEBUG(LOG_WARNING, ("pppos_write[%d]: alloc fail\n", ppp->netif->num));
     LINK_STATS_INC(link.memerr);
@@ -220,6 +219,8 @@ pppos_write(ppp_pcb *ppp, void *ctx, struct pbuf *p)
     return ERR_MEM;
   }
 
+  /* Empty the buffer */
+  nb->len = 0;
   /* Set nb->tot_len to actual payload length */
   nb->tot_len = p->len;
 
@@ -258,10 +259,9 @@ pppos_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *pb, u16_t protocol)
   err_t err;
   LWIP_UNUSED_ARG(ppp);
 
-  /* Grab an output buffer. Using PBUF_POOL here for tx is ok since the pbuf
-     gets freed by 'pppos_output_last' before this function returns and thus
-     cannot starve rx. */
-  nb = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);
+  /* Grab an output buffer. Assume PBUF_POOL_BUFSIZE is an acceptable
+   * chunk size for Tx as well. */
+  nb = pbuf_alloc(PBUF_RAW, PBUF_POOL_BUFSIZE, PBUF_RAM);
   if (nb == NULL) {
     PPPDEBUG(LOG_WARNING, ("pppos_netif_output[%d]: alloc fail\n", ppp->netif->num));
     LINK_STATS_INC(link.memerr);
@@ -270,6 +270,8 @@ pppos_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *pb, u16_t protocol)
     return ERR_MEM;
   }
 
+  /* Empty the buffer */
+  nb->len = 0;
   /* Set nb->tot_len to actual payload length */
   nb->tot_len = pb->tot_len;