diff --git a/CHANGELOG b/CHANGELOG
index b56b661a..b6dddc7a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -13,6 +13,10 @@ HISTORY
 
   ++ New features:
 
+  2010-05-16: Simon Goldschmidt
+  * def.h: task #10391: Add preprocessor-macros for compile-time htonl
+    calculation (and use them throughout the stack where applicable)
+
   2010-05-16: Simon Goldschmidt
   * opt.h, memp_std.h, memp.c, ppp_oe.h/.c: PPPoE now uses its own MEMP pool
     instead of the heap (moved struct pppoe_softc from ppp_oe.c to ppp_oe.h)
diff --git a/src/core/dhcp.c b/src/core/dhcp.c
index 6a11ddcc..05816f58 100644
--- a/src/core/dhcp.c
+++ b/src/core/dhcp.c
@@ -942,11 +942,11 @@ dhcp_bind(struct netif *netif)
     /* subnet mask not given, choose a safe subnet mask given the network class */
     u8_t first_octet = ip4_addr1(&dhcp->offered_ip_addr);
     if (first_octet <= 127) {
-      ip4_addr_set_u32(&sn_mask, htonl(0xff000000));
+      ip4_addr_set_u32(&sn_mask, PP_HTONL(0xff000000));
     } else if (first_octet >= 192) {
-      ip4_addr_set_u32(&sn_mask, htonl(0xffffff00));
+      ip4_addr_set_u32(&sn_mask, PP_HTONL(0xffffff00));
     } else {
-      ip4_addr_set_u32(&sn_mask, htonl(0xffff0000));
+      ip4_addr_set_u32(&sn_mask, PP_HTONL(0xffff0000));
     }
   }
 
@@ -956,7 +956,7 @@ dhcp_bind(struct netif *netif)
     /* copy network address */
     ip_addr_get_network(&gw_addr, &dhcp->offered_ip_addr, &sn_mask);
     /* use first host address on network as gateway */
-    ip4_addr_set_u32(&gw_addr, ip4_addr_get_u32(&gw_addr) | htonl(0x00000001));
+    ip4_addr_set_u32(&gw_addr, ip4_addr_get_u32(&gw_addr) | PP_HTONL(0x00000001));
   }
 
 #if LWIP_DHCP_AUTOIP_COOP
@@ -1663,7 +1663,7 @@ dhcp_create_msg(struct netif *netif, struct dhcp *dhcp, u8_t message_type)
   for (i = 0; i < DHCP_FILE_LEN; i++) {
     dhcp->msg_out->file[i] = 0;
   }
-  dhcp->msg_out->cookie = htonl(DHCP_MAGIC_COOKIE);
+  dhcp->msg_out->cookie = PP_HTONL(DHCP_MAGIC_COOKIE);
   dhcp->options_out_len = 0;
   /* fill options field with an incrementing array (for debugging purposes) */
   for (i = 0; i < DHCP_OPTIONS_LEN; i++) {
diff --git a/src/core/dns.c b/src/core/dns.c
index 205b2917..c55a84dd 100644
--- a/src/core/dns.c
+++ b/src/core/dns.c
@@ -582,7 +582,7 @@ dns_send(u8_t numdns, const char* name, u8_t id)
     memset(hdr, 0, SIZEOF_DNS_HDR);
     hdr->id = htons(id);
     hdr->flags1 = DNS_FLAG1_RD;
-    hdr->numquestions = htons(1);
+    hdr->numquestions = PP_HTONS(1);
     query = (char*)hdr + SIZEOF_DNS_HDR;
     pHostname = name;
     --pHostname;
@@ -602,8 +602,8 @@ dns_send(u8_t numdns, const char* name, u8_t id)
     *query++='\0';
 
     /* fill dns query */
-    qry.type = htons(DNS_RRTYPE_A);
-    qry.cls = htons(DNS_RRCLASS_IN);
+    qry.type = PP_HTONS(DNS_RRTYPE_A);
+    qry.cls = PP_HTONS(DNS_RRCLASS_IN);
     SMEMCPY(query, &qry, SIZEOF_DNS_QUERY);
 
     /* resize pbuf to the exact dns query */
@@ -791,8 +791,8 @@ dns_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t
 
           /* Check for IP address type and Internet class. Others are discarded. */
           SMEMCPY(&ans, pHostname, SIZEOF_DNS_ANSWER);
-          if((ans.type == htons(DNS_RRTYPE_A)) && (ans.cls == htons(DNS_RRCLASS_IN)) &&
-             (ans.len == htons(sizeof(ip_addr_t))) ) {
+          if((ans.type == PP_HTONS(DNS_RRTYPE_A)) && (ans.cls == PP_HTONS(DNS_RRCLASS_IN)) &&
+             (ans.len == PP_HTONS(sizeof(ip_addr_t))) ) {
             /* read the answer resource record's TTL, and maximize it if needed */
             pEntry->ttl = ntohl(ans.ttl);
             if (pEntry->ttl > DNS_MAX_TTL) {
diff --git a/src/core/ipv4/icmp.c b/src/core/ipv4/icmp.c
index b9326bd9..e12a0e17 100644
--- a/src/core/ipv4/icmp.c
+++ b/src/core/ipv4/icmp.c
@@ -193,10 +193,10 @@ icmp_input(struct pbuf *p, struct netif *inp)
     ip_addr_copy(iphdr->dest, tmpaddr);
     ICMPH_TYPE_SET(iecho, ICMP_ER);
     /* adjust the checksum */
-    if (iecho->chksum >= htons(0xffff - (ICMP_ECHO << 8))) {
-      iecho->chksum += htons(ICMP_ECHO << 8) + 1;
+    if (iecho->chksum >= PP_HTONS(0xffff - (ICMP_ECHO << 8))) {
+      iecho->chksum += PP_HTONS(ICMP_ECHO << 8) + 1;
     } else {
-      iecho->chksum += htons(ICMP_ECHO << 8);
+      iecho->chksum += PP_HTONS(ICMP_ECHO << 8);
     }
 
     /* Set the correct TTL and recalculate the header checksum. */
diff --git a/src/core/ipv4/igmp.c b/src/core/ipv4/igmp.c
index 80045dca..1e2427fd 100644
--- a/src/core/ipv4/igmp.c
+++ b/src/core/ipv4/igmp.c
@@ -759,7 +759,7 @@ igmp_ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest, struct netif
 {
   /* This is the "router alert" option */
   u16_t ra[2];
-  ra[0] = htons(ROUTER_ALERT);
+  ra[0] = PP_HTONS(ROUTER_ALERT);
   ra[1] = 0x0000; /* Router shall examine packet */
   IGMP_STATS_INC(igmp.xmit);
   return ip_output_if_opt(p, src, dest, IGMP_TTL, 0, IP_PROTO_IGMP, netif, ra, ROUTER_ALERTLEN);
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index dd48ce27..5e434cd1 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -174,10 +174,10 @@ ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
   }
 
   /* Incrementally update the IP checksum. */
-  if (IPH_CHKSUM(iphdr) >= htons(0xffff - 0x100)) {
-    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100) + 1);
+  if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffff - 0x100)) {
+    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1);
   } else {
-    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100));
+    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100));
   }
 
   LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
@@ -346,9 +346,10 @@ ip_input(struct pbuf *p, struct netif *inp)
   if (netif == NULL) {
     /* remote port is DHCP server? */
     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
+      struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen);
       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
-        ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest)));
-      if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest) == DHCP_CLIENT_PORT) {
+        ntohs(udphdr->dest)));
+      if (udphdr->dest == PP_NTOHS(DHCP_CLIENT_PORT)) {
         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: DHCP packet accepted.\n"));
         netif = inp;
         check_ip_src = 0;
@@ -394,10 +395,10 @@ ip_input(struct pbuf *p, struct netif *inp)
     return ERR_OK;
   }
   /* packet consists of multiple fragments? */
-  if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
+  if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
     LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip_reass()\n",
-      ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
+      ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
     /* reassemble the packet*/
     p = ip_reass(p);
     /* packet not fully reassembled yet? */
diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index aa978b7c..1ffdfacd 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -555,7 +555,7 @@ ip_reass(struct pbuf *p)
    * to an existing one */
 
   /* check for 'no more fragments', and update queue entry*/
-  if ((ntohs(IPH_OFFSET(fraghdr)) & IP_MF) == 0) {
+  if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) {
     ipr->flags |= IP_REASS_FLAG_LASTFRAG;
     ipr->datagram_len = offset + len;
     LWIP_DEBUGF(IP_REASS_DEBUG,
@@ -708,7 +708,7 @@ ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest)
       return ERR_MEM;
     }
     LWIP_ASSERT("this needs a pbuf in one piece!",
-      (p->len == p->tot_len) && (p->next == NULL));
+      (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
     poff += pbuf_copy_partial(p, rambuf->payload, cop, poff);
     /* make room for the IP header */
     if(pbuf_header(rambuf, IP_HLEN)) {
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index a2bce4d2..bbe1d3c9 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -826,7 +826,7 @@ static void
 tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts)
 {
   /* Pad with two NOP options to make everything nicely aligned */
-  opts[0] = htonl(0x0101080A);
+  opts[0] = PP_HTONL(0x0101080A);
   opts[1] = htonl(sys_now());
   opts[2] = htonl(pcb->ts_recent);
 }
@@ -1207,7 +1207,7 @@ tcp_rst(u32_t seqno, u32_t ackno,
   tcphdr->seqno = htonl(seqno);
   tcphdr->ackno = htonl(ackno);
   TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK);
-  tcphdr->wnd = htons(TCP_WND);
+  tcphdr->wnd = PP_HTONS(TCP_WND);
   tcphdr->chksum = 0;
   tcphdr->urgp = 0;
 
diff --git a/src/include/ipv4/lwip/ip_addr.h b/src/include/ipv4/lwip/ip_addr.h
index d26c43c9..65636f54 100644
--- a/src/include/ipv4/lwip/ip_addr.h
+++ b/src/include/ipv4/lwip/ip_addr.h
@@ -158,7 +158,7 @@ extern const ip_addr_t ip_addr_broadcast;
 /** Set address to IPADDR_ANY (no need for htonl()) */
 #define ip_addr_set_any(ipaddr)       ((ipaddr)->addr = IPADDR_ANY)
 /** Set address to loopback address */
-#define ip_addr_set_loopback(ipaddr)  ((ipaddr)->addr = htonl(IPADDR_LOOPBACK))
+#define ip_addr_set_loopback(ipaddr)  ((ipaddr)->addr = PP_HTONL(IPADDR_LOOPBACK))
 /** Safely copy one IP address to another and change byte order
  * from host- to network-order. */
 #define ip_addr_set_hton(dest, src) ((dest)->addr = \
@@ -190,9 +190,9 @@ extern const ip_addr_t ip_addr_broadcast;
 
 u8_t ip_addr_isbroadcast(const ip_addr_t *, const struct netif *);
 
-#define ip_addr_ismulticast(addr1) (((addr1)->addr & ntohl(0xf0000000UL)) == ntohl(0xe0000000UL))
+#define ip_addr_ismulticast(addr1) (((addr1)->addr & PP_HTONL(0xf0000000UL)) == PP_HTONL(0xe0000000UL))
 
-#define ip_addr_islinklocal(addr1) (((addr1)->addr & ntohl(0xffff0000UL)) == ntohl(0xa9fe0000UL))
+#define ip_addr_islinklocal(addr1) (((addr1)->addr & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xa9fe0000UL))
 
 #define ip_addr_debug_print(debug, ipaddr) \
   LWIP_DEBUGF(debug, ("%"U16_F".%"U16_F".%"U16_F".%"U16_F,             \
diff --git a/src/include/lwip/tcp_impl.h b/src/include/lwip/tcp_impl.h
index c9a989d9..320b88ef 100644
--- a/src/include/lwip/tcp_impl.h
+++ b/src/include/lwip/tcp_impl.h
@@ -176,7 +176,7 @@ PACK_STRUCT_END
 
 #define TCPH_OFFSET_SET(phdr, offset) (phdr)->_hdrlen_rsvd_flags = htons(((offset) << 8) | TCPH_FLAGS(phdr))
 #define TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | TCPH_FLAGS(phdr))
-#define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & htons((u16_t)(~(u16_t)(TCP_FLAGS)))) | htons(flags))
+#define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(u16_t)(TCP_FLAGS)))) | htons(flags))
 #define TCPH_HDRLEN_FLAGS_SET(phdr, len, flags) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | (flags))
 
 #define TCPH_SET_FLAG(phdr, flags ) (phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags | htons(flags))
@@ -302,10 +302,10 @@ struct tcp_seg {
   (flags & TF_SEG_OPTS_TS  ? 12 : 0)
 
 /** This returns a TCP header option for MSS in an u32_t */
-#define TCP_BUILD_MSS_OPTION(x) (x) = htonl(((u32_t)2 << 24) |          \
-                                            ((u32_t)4 << 16) |          \
-                                            (((u32_t)TCP_MSS / 256) << 8) | \
-                                            (TCP_MSS & 255))
+#define TCP_BUILD_MSS_OPTION(x) (x) = PP_HTONL(((u32_t)2 << 24) |          \
+                                               ((u32_t)4 << 16) |          \
+                                               (((u32_t)TCP_MSS / 256) << 8) | \
+                                               (TCP_MSS & 255))
 
 /* Global variables: */
 extern struct tcp_pcb *tcp_input_pcb;
diff --git a/src/netif/etharp.c b/src/netif/etharp.c
index 42bce4b4..da10abb0 100644
--- a/src/netif/etharp.c
+++ b/src/netif/etharp.c
@@ -423,7 +423,7 @@ etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct
               (netif->hwaddr_len == ETHARP_HWADDR_LEN));
   ETHADDR32_COPY(&ethhdr->dest, dst);
   ETHADDR16_COPY(&ethhdr->src, src);
-  ethhdr->type = htons(ETHTYPE_IP);
+  ethhdr->type = PP_HTONS(ETHTYPE_IP);
   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_send_ip: sending packet %p\n", (void *)p));
   /* send the packet */
   return netif->linkoutput(netif, p);
@@ -700,10 +700,10 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
 #endif /* ETHARP_SUPPORT_VLAN */
 
   /* RFC 826 "Packet Reception": */
-  if ((hdr->hwtype != htons(HWTYPE_ETHERNET)) ||
-      (hdr->_hwlen_protolen != htons((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t))) ||
-      (hdr->proto != htons(ETHTYPE_IP)) ||
-      (ethhdr->type != htons(ETHTYPE_ARP)))  {
+  if ((hdr->hwtype != PP_HTONS(HWTYPE_ETHERNET)) ||
+      (hdr->_hwlen_protolen != PP_HTONS((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t))) ||
+      (hdr->proto != PP_HTONS(ETHTYPE_IP)) ||
+      (ethhdr->type != PP_HTONS(ETHTYPE_ARP)))  {
     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
       ("etharp_arp_input: packet dropped, wrong hw type, hwlen, proto, protolen or ethernet type (%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F"/%"U16_F")\n",
       hdr->hwtype, ARPH_HWLEN(hdr), hdr->proto, ARPH_PROTOLEN(hdr), ethhdr->type));
@@ -743,9 +743,9 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
                    for_us ? ETHARP_FLAG_TRY_HARD : ETHARP_FLAG_FIND_ONLY);
 
   /* now act on the message itself */
-  switch (htons(hdr->opcode)) {
+  switch (hdr->opcode) {
   /* ARP request? */
-  case ARP_REQUEST:
+  case PP_HTONS(ARP_REQUEST):
     /* ARP request. If it asked for our address, we send out a
      * reply. In any case, we time-stamp any existing ARP entry,
      * and possiby send out an IP packet that was queued on it. */
@@ -796,7 +796,7 @@ etharp_arp_input(struct netif *netif, struct eth_addr *ethaddr, struct pbuf *p)
       LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: ARP request was not for us.\n"));
     }
     break;
-  case ARP_REPLY:
+  case PP_HTONS(ARP_REPLY):
     /* ARP reply. We already updated the ARP cache earlier. */
     LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_arp_input: incoming ARP reply\n"));
 #if (LWIP_DHCP && DHCP_DOES_ARP_CHECK)
@@ -1151,12 +1151,12 @@ etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
   IPADDR2_COPY(&hdr->sipaddr, ipsrc_addr);
   IPADDR2_COPY(&hdr->dipaddr, ipdst_addr);
 
-  hdr->hwtype = htons(HWTYPE_ETHERNET);
-  hdr->proto = htons(ETHTYPE_IP);
+  hdr->hwtype = PP_HTONS(HWTYPE_ETHERNET);
+  hdr->proto = PP_HTONS(ETHTYPE_IP);
   /* set hwlen and protolen together */
-  hdr->_hwlen_protolen = htons((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t));
+  hdr->_hwlen_protolen = PP_HTONS((ETHARP_HWADDR_LEN << 8) | sizeof(ip_addr_t));
 
-  ethhdr->type = htons(ETHTYPE_ARP);
+  ethhdr->type = PP_HTONS(ETHTYPE_ARP);
   /* send ARP query */
   result = netif->linkoutput(netif, p);
   ETHARP_STATS_INC(etharp.xmit);
@@ -1211,9 +1211,9 @@ ethernet_input(struct pbuf *p, struct netif *netif)
      (unsigned)ethhdr->src.addr[3], (unsigned)ethhdr->src.addr[4], (unsigned)ethhdr->src.addr[5],
      (unsigned)htons(ethhdr->type)));
 
-  type = htons(ethhdr->type);
+  type = ethhdr->type;
 #if ETHARP_SUPPORT_VLAN
-  if (type == ETHTYPE_VLAN) {
+  if (type == PP_HTONS(ETHTYPE_VLAN)) {
     struct eth_vlan_hdr *vlan = (struct eth_vlan_hdr*)(((char*)ethhdr) + SIZEOF_ETH_HDR);
 #ifdef ETHARP_VLAN_CHECK /* if not, allow all VLANs */
     if (VLAN_ID(vlan) != ETHARP_VLAN_CHECK) {
@@ -1222,18 +1222,18 @@ ethernet_input(struct pbuf *p, struct netif *netif)
       return ERR_OK;
     }
 #endif /* ETHARP_VLAN_CHECK */
-    type = htons(vlan->tpid);
+    type = vlan->tpid;
   }
 #endif /* ETHARP_SUPPORT_VLAN */
 
 #if LWIP_ARP_FILTER_NETIF
-  netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, type);
+  netif = LWIP_ARP_FILTER_NETIF_FN(p, netif, htons(type));
 #endif /* LWIP_ARP_FILTER_NETIF*/
 
   switch (type) {
 #if LWIP_ARP
     /* IP packet? */
-    case ETHTYPE_IP:
+    case PP_HTONS(ETHTYPE_IP):
       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
         goto free_and_return;
       }
@@ -1251,7 +1251,7 @@ ethernet_input(struct pbuf *p, struct netif *netif)
       }
       break;
       
-    case ETHTYPE_ARP:
+    case PP_HTONS(ETHTYPE_ARP):
       if (!(netif->flags & NETIF_FLAG_ETHARP)) {
         goto free_and_return;
       }
@@ -1260,11 +1260,11 @@ ethernet_input(struct pbuf *p, struct netif *netif)
       break;
 #endif /* LWIP_ARP */
 #if PPPOE_SUPPORT
-    case ETHTYPE_PPPOEDISC: /* PPP Over Ethernet Discovery Stage */
+    case PP_HTONS(ETHTYPE_PPPOEDISC): /* PPP Over Ethernet Discovery Stage */
       pppoe_disc_input(netif, p);
       break;
 
-    case ETHTYPE_PPPOE: /* PPP Over Ethernet Session Stage */
+    case PP_HTONS(ETHTYPE_PPPOE): /* PPP Over Ethernet Session Stage */
       pppoe_data_input(netif, p);
       break;
 #endif /* PPPOE_SUPPORT */
diff --git a/src/netif/ppp/chpms.c b/src/netif/ppp/chpms.c
index c0aa25c6..83acefce 100644
--- a/src/netif/ppp/chpms.c
+++ b/src/netif/ppp/chpms.c
@@ -325,7 +325,7 @@ ChapMS_NT( char *rchallenge,
   MDupdate(&md4Context, unicodePassword, secret_len * 2 * 8);  /* Unicode is 2 bytes/char, *8 for bit count */
 
   if (low_byte_first == -1) {
-    low_byte_first = (htons((unsigned short int)1) != 1);
+    low_byte_first = (PP_HTONS((unsigned short int)1) != 1);
   }
   if (low_byte_first == 0) {
     /* @todo: arg type - u_long* or u_int* ? */
diff --git a/src/netif/ppp/ppp.c b/src/netif/ppp/ppp.c
index 4674f06e..2a280ff0 100644
--- a/src/netif/ppp/ppp.c
+++ b/src/netif/ppp/ppp.c
@@ -439,7 +439,7 @@ pppInit(void)
 
   magicInit();
 
-  subnetMask = htonl(0xffffff00);
+  subnetMask = PP_HTONL(0xffffff00);
 
   for (i = 0; i < NUM_PPP; i++) {
     /* Initialize each protocol to the standard option set. */
diff --git a/src/netif/ppp/ppp_oe.c b/src/netif/ppp/ppp_oe.c
index 5e9cbcef..040a0bc9 100644
--- a/src/netif/ppp/ppp_oe.c
+++ b/src/netif/ppp/ppp_oe.c
@@ -958,7 +958,7 @@ pppoe_send_padt(struct netif *outgoing_if, u_int session, const u8_t *dest)
   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
 
   ethhdr = (struct eth_hdr *)pb->payload;
-  ethhdr->type = htons(ETHTYPE_PPPOEDISC);
+  ethhdr->type = PP_HTONS(ETHTYPE_PPPOEDISC);
   MEMCPY(ethhdr->dest.addr, dest, sizeof(ethhdr->dest.addr));
   MEMCPY(ethhdr->src.addr, ((struct eth_addr *)outgoing_if->hwaddr)->addr, sizeof(ethhdr->src.addr));
 
diff --git a/src/netif/ppp/vj.c b/src/netif/ppp/vj.c
index 5ff7d38a..b7f2d54c 100644
--- a/src/netif/ppp/vj.c
+++ b/src/netif/ppp/vj.c
@@ -160,7 +160,7 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf *pb)
    * `compressible' (i.e., ACK isn't set or some other control bit is
    * set).  
    */
-  if ((IPH_OFFSET(ip) & htons(0x3fff)) || pb->tot_len < 40) {
+  if ((IPH_OFFSET(ip) & PP_HTONS(0x3fff)) || pb->tot_len < 40) {
     return (TYPE_IP);
   }
   th = (struct tcp_hdr *)&((long *)ip)[hlen];