diff --git a/src/core/raw.c b/src/core/raw.c
index 0e0bce2f..d034517f 100644
--- a/src/core/raw.c
+++ b/src/core/raw.c
@@ -248,7 +248,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
 
   header_size = (
 #if LWIP_IPV4 && LWIP_IPV6
-    PCB_ISIPV6(pcb) ? IP6_HLEN : IP_HLEN);
+    IP_IS_V6(ipaddr) ? IP6_HLEN : IP_HLEN);
 #elif LWIP_IPV4
     IP_HLEN);
 #else
@@ -279,7 +279,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
     }
   }
 
-  netif = ip_route(PCB_ISIPV6(pcb), &pcb->local_ip, dst_ip);
+  netif = ip_route(IP_IS_V6(dst_ip), &pcb->local_ip, dst_ip);
   if (netif == NULL) {
     LWIP_DEBUGF(RAW_DEBUG | LWIP_DBG_LEVEL_WARNING, ("raw_sendto: No route to "));
     ip_addr_debug_print(RAW_DEBUG | LWIP_DBG_LEVEL_WARNING, dst_ip);
@@ -291,7 +291,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
   }
 
 #if IP_SOF_BROADCAST
-  if (!PCB_ISIPV6(pcb))
+  if (!IP_IS_V6(ipaddr))
   {
     /* broadcast filter? */
     if (!ip_get_option(pcb, SOF_BROADCAST) && ip_addr_isbroadcast(ipaddr, netif)) {
@@ -307,7 +307,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
 
   if (ip_addr_isany(&pcb->local_ip)) {
     /* use outgoing network interface IP address as source address */
-    src_ip = ip_netif_get_local_ip(PCB_ISIPV6(pcb), netif, dst_ip);
+    src_ip = ip_netif_get_local_ip(IP_IS_V6(dst_ip), netif, dst_ip);
 #if LWIP_IPV6
     if (src_ip == NULL) {
       if (q != p) {
@@ -324,7 +324,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
 #if LWIP_IPV6
   /* If requested, based on the IPV6_CHECKSUM socket option per RFC3542,
      compute the checksum and update the checksum in the payload. */
-  if (PCB_ISIPV6(pcb) && pcb->chksum_reqd) {
+  if (IP_IS_V6(dst_ip) && pcb->chksum_reqd) {
     u16_t chksum = ip6_chksum_pseudo(p, pcb->protocol, p->tot_len, ip_2_ip6(src_ip), ip_2_ip6(dst_ip));
     LWIP_ASSERT("Checksum must fit into first pbuf", p->len >= (pcb->chksum_offset + 2));
     SMEMCPY(((u8_t *)p->payload) + pcb->chksum_offset, &chksum, sizeof(u16_t));
@@ -332,7 +332,7 @@ raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
 #endif
 
   NETIF_SET_HWADDRHINT(netif, &pcb->addr_hint);
-  err = ip_output_if(PCB_ISIPV6(pcb), q, src_ip, dst_ip, pcb->ttl, pcb->tos, pcb->protocol, netif);
+  err = ip_output_if(IP_IS_V6(dst_ip), q, src_ip, dst_ip, pcb->ttl, pcb->tos, pcb->protocol, netif);
   NETIF_SET_HWADDRHINT(netif, NULL);
 
   /* did we chain a header earlier? */
diff --git a/src/core/tcp.c b/src/core/tcp.c
index c6f0cb52..650c075b 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -769,7 +769,7 @@ tcp_connect(struct tcp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port,
     /* no local IP address set, yet. */
     struct netif *netif;
     const ip_addr_t *local_ip;
-    ip_route_get_local_ip(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip, netif, local_ip);
+    ip_route_get_local_ip(IP_IS_V6(ipaddr), &pcb->local_ip, &pcb->remote_ip, netif, local_ip);
     if ((netif == NULL) || (local_ip == NULL)) {
       /* Don't even try to send a SYN packet if we have no route
          since that will fail. */
@@ -823,7 +823,7 @@ tcp_connect(struct tcp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port,
      The send MSS is updated when an MSS option is received. */
   pcb->mss = (TCP_MSS > 536) ? 536 : TCP_MSS;
 #if TCP_CALCULATE_EFF_SEND_MSS
-  pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb));
+  pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip, IP_IS_V6_VAL(pcb->remote_ip));
 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
   pcb->cwnd = 1;
   pcb->ssthresh = TCP_WND;
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index 6ab2ecf1..b33c0867 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -740,7 +740,7 @@ tcp_process(struct tcp_pcb *pcb)
 
 #if TCP_CALCULATE_EFF_SEND_MSS
       pcb->mss = tcp_eff_send_mss(pcb->mss, &pcb->local_ip, &pcb->remote_ip,
-        PCB_ISIPV6(pcb));
+        IP_IS_V6_VAL(pcb->remote_ip));
 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
 
       /* Set ssthresh again after changing 'mss' and 'snd_wnd' */
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index feb6c7ea..5de643fa 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -930,7 +930,7 @@ tcp_send_empty_ack(struct tcp_pcb *pcb)
   }
 #endif
 
-  netif = ip_route(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip);
+  netif = ip_route(IP_IS_V6_VAL(pcb->remote_ip), &pcb->local_ip, &pcb->remote_ip);
   if (netif == NULL) {
     err = ERR_RTE;
   } else {
@@ -941,7 +941,7 @@ tcp_send_empty_ack(struct tcp_pcb *pcb)
     }
 #endif
     NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
-    err = ip_output_if(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip,
+    err = ip_output_if(IP_IS_V6_VAL(pcb->remote_ip), p, &pcb->local_ip, &pcb->remote_ip,
       pcb->ttl, pcb->tos, IP_PROTO_TCP, netif);
     NETIF_SET_HWADDRHINT(netif, NULL);
   }
@@ -1161,7 +1161,7 @@ tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
   if (seg->flags & TF_SEG_OPTS_MSS) {
     u16_t mss;
 #if TCP_CALCULATE_EFF_SEND_MSS
-    mss = tcp_eff_send_mss(TCP_MSS, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb));
+    mss = tcp_eff_send_mss(TCP_MSS, &pcb->local_ip, &pcb->remote_ip, IP_IS_V6_VAL(pcb->remote_ip));
 #else /* TCP_CALCULATE_EFF_SEND_MSS */
     mss = TCP_MSS;
 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
@@ -1189,14 +1189,14 @@ tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
     pcb->rtime = 0;
   }
 
-  netif = ip_route(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip);
+  netif = ip_route(IP_IS_V6_VAL(pcb->remote_ip), &pcb->local_ip, &pcb->remote_ip);
   if (netif == NULL) {
     return ERR_RTE;
   }
 
   /* If we don't have a local IP address, we get one from netif */
   if (ip_addr_isany(&pcb->local_ip)) {
-    const ip_addr_t *local_ip = ip_netif_get_local_ip(PCB_ISIPV6(pcb), netif,
+    const ip_addr_t *local_ip = ip_netif_get_local_ip(IP_IS_V6_VAL(pcb->remote_ip), netif,
       &pcb->remote_ip);
     if (local_ip == NULL) {
       return ERR_RTE;
@@ -1262,7 +1262,7 @@ tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
   TCP_STATS_INC(tcp.xmit);
 
   NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
-  err = ip_output_if(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+  err = ip_output_if(IP_IS_V6_VAL(pcb->remote_ip), seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
     pcb->tos, IP_PROTO_TCP, netif);
   NETIF_SET_HWADDRHINT(netif, NULL);
   return err;
@@ -1493,7 +1493,7 @@ tcp_keepalive(struct tcp_pcb *pcb)
                 ("tcp_keepalive: could not allocate memory for pbuf\n"));
     return ERR_MEM;
   }
-  netif = ip_route(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip);
+  netif = ip_route(IP_IS_V6_VAL(pcb->remote_ip), &pcb->local_ip, &pcb->remote_ip);
   if (netif == NULL) {
     err = ERR_RTE;
   } else {
@@ -1508,7 +1508,7 @@ tcp_keepalive(struct tcp_pcb *pcb)
 
     /* Send output to IP */
     NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
-    err = ip_output_if(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+    err = ip_output_if(IP_IS_V6_VAL(pcb->remote_ip), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
       0, IP_PROTO_TCP, netif);
     NETIF_SET_HWADDRHINT(netif, NULL);
   }
@@ -1581,7 +1581,7 @@ tcp_zero_window_probe(struct tcp_pcb *pcb)
     pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
   }
 
-  netif = ip_route(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip);
+  netif = ip_route(IP_IS_V6_VAL(pcb->remote_ip), &pcb->local_ip, &pcb->remote_ip);
   if (netif == NULL) {
     err = ERR_RTE;
   } else {
@@ -1595,7 +1595,7 @@ tcp_zero_window_probe(struct tcp_pcb *pcb)
 
     /* Send output to IP */
     NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
-    err = ip_output_if(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+    err = ip_output_if(IP_IS_V6_VAL(pcb->remote_ip), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
       0, IP_PROTO_TCP, netif);
     NETIF_SET_HWADDRHINT(netif, NULL);
   }