diff --git a/contrib/ports/unix/setup-tapif b/contrib/ports/unix/setup-tapif
index d5c4935d..eecc23bd 100755
--- a/contrib/ports/unix/setup-tapif
+++ b/contrib/ports/unix/setup-tapif
@@ -12,6 +12,9 @@
 # Enter 192.168.1.200 or "http://lwip.local/" (Zeroconf)
 # in your webbrowser to see example_app webpage.
 
+# N.b. you must disable USE_DHCP and USE_AUTOIP in lwipcfg.h for the static 
+# ip 192.168.1.200 to work in tapif
+
 export PRECONFIGURED_TAPIF=tap0
 
 sudo ip tuntap add dev $PRECONFIGURED_TAPIF mode tap user `whoami`
diff --git a/src/api/sockets.c b/src/api/sockets.c
index b97bdd7e..7f5eaf49 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -2926,6 +2926,7 @@ lwip_sockopt_to_ipopt(int optname)
 static void
 lwip_getsockopt_impl_ipv6_checksum(int s, struct lwip_sock* sock, void* optval)
 {
+  LWIP_UNUSED_ARG(s);
   if (sock->conn->pcb.raw->chksum_reqd == 0) {
     *(int*)optval = -1;
   }
@@ -2939,6 +2940,7 @@ lwip_getsockopt_impl_ipv6_checksum(int s, struct lwip_sock* sock, void* optval)
 static int
 lwip_setsockopt_impl_ipv6_checksum(int s, struct lwip_sock* sock, const void* optval, socklen_t optlen)
 {
+  LWIP_UNUSED_ARG(s);
   /* It should not be possible to disable the checksum generation with ICMPv6
    * as per RFC 3542 chapter 3.1 */
   if (sock->conn->pcb.raw->protocol == IPPROTO_ICMPV6) {