diff --git a/doc/ppp.txt b/doc/ppp.txt
index 8b0acdf0..7a9ba674 100644
--- a/doc/ppp.txt
+++ b/doc/ppp.txt
@@ -419,3 +419,5 @@ from previous lwIP version is pretty easy:
   conditional.
 
 * PPPoS now requires a serial output callback
+
+* PPP_MAXIDLEFLAG is now in ms instead of jiffies
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index c5b25725..5aea2d83 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -2394,7 +2394,7 @@
 #endif
 
 /**
- * PPP_MAXIDLEFLAG: Max Xmit idle time (in jiffies) before resend flag char.
+ * PPP_MAXIDLEFLAG: Max Xmit idle time (in ms) before resend flag char.
  */
 #ifndef PPP_MAXIDLEFLAG
 #define PPP_MAXIDLEFLAG                 100
diff --git a/src/netif/ppp/pppos.c b/src/netif/ppp/pppos.c
index 95411229..f1d922dd 100644
--- a/src/netif/ppp/pppos.c
+++ b/src/netif/ppp/pppos.c
@@ -215,7 +215,7 @@ pppos_write(ppp_pcb *ppp, void *ctx, struct pbuf *p)
   /* If the link has been idle, we'll send a fresh flag character to
    * flush any noise. */
   err = ERR_OK;
-  if ((sys_jiffies() - pppos->last_xmit) >= PPP_MAXIDLEFLAG) {
+  if ((sys_now() - pppos->last_xmit) >= PPP_MAXIDLEFLAG) {
     err = pppos_output_append(pppos, err,  nb, PPP_FLAG, 0, NULL);
   }
 
@@ -260,7 +260,7 @@ pppos_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *pb, u16_t protocol)
   /* If the link has been idle, we'll send a fresh flag character to
    * flush any noise. */
   err = ERR_OK;
-  if ((sys_jiffies() - pppos->last_xmit) >= PPP_MAXIDLEFLAG) {
+  if ((sys_now() - pppos->last_xmit) >= PPP_MAXIDLEFLAG) {
     err = pppos_output_append(pppos, err,  nb, PPP_FLAG, 0, NULL);
   }
 
@@ -879,7 +879,7 @@ pppos_output_last(pppos_pcb *pppos, err_t err, struct pbuf *nb, u16_t *fcs)
     }
   }
 
-  pppos->last_xmit = sys_jiffies();
+  pppos->last_xmit = sys_now();
   MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, nb->tot_len);
   MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
   LINK_STATS_INC(link.xmit);