diff --git a/src/netif/ppp/ppp_oe.c b/src/netif/ppp/ppp_oe.c
index b78ec301..a9cf063a 100644
--- a/src/netif/ppp/ppp_oe.c
+++ b/src/netif/ppp/ppp_oe.c
@@ -738,7 +738,7 @@ pppoe_timeout(void *arg)
        * We only enter slow retry mode if IFF_LINK1 (aka autodial)
        * is not set.
        */
-      if (sc->sc_padi_retried < UCHAR_MAX) {
+      if (sc->sc_padi_retried < 0xff) {
         sc->sc_padi_retried++;
       }
       if (!sc->pcb->settings.persist && sc->sc_padi_retried >= PPPOE_DISC_MAXPADI) {
diff --git a/src/netif/ppp/pppol2tp.c b/src/netif/ppp/pppol2tp.c
index fd85616a..d8b20832 100644
--- a/src/netif/ppp/pppol2tp.c
+++ b/src/netif/ppp/pppol2tp.c
@@ -567,7 +567,7 @@ static void pppol2tp_timeout(void *arg) {
   switch (l2tp->phase) {
     case PPPOL2TP_STATE_SCCRQ_SENT:
       /* backoff wait */
-      if (l2tp->sccrq_retried < UCHAR_MAX) {
+      if (l2tp->sccrq_retried < 0xff) {
         l2tp->sccrq_retried++;
       }
       if (!l2tp->ppp->settings.persist && l2tp->sccrq_retried >= PPPOL2TP_MAXSCCRQ) {