diff --git a/CHANGELOG b/CHANGELOG
index 190d97ab..34473b35 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -23,6 +23,9 @@ HISTORY
 
   ++ New features:
 
+  2007-04-04 Simon Goldschmidt
+  * arch.h, dhcp.c, :
+
   2007-03-28 Frédéric Bernon
   * opt.h, netif.h, dhcp.h, dhcp.c: New configuration option LWIP_NETIF_HOSTNAME allow to
     define a hostname in netif struct (this is just a pointer, so, you can use a hardcoded
diff --git a/src/api/api_msg.c b/src/api/api_msg.c
index 39ad6e02..031cc752 100644
--- a/src/api/api_msg.c
+++ b/src/api/api_msg.c
@@ -47,7 +47,8 @@ recv_raw(void *arg, struct raw_pcb *pcb, struct pbuf *p,
   struct netconn *conn;
 
   conn = arg;
-  if (!conn) return 0;
+  if (!conn)
+    return 0;
 
   if (conn->recvmbox != SYS_MBOX_NULL) {
     if (!(buf = memp_malloc(MEMP_NETBUF))) {
@@ -78,7 +79,7 @@ recv_udp(void *arg, struct udp_pcb *pcb, struct pbuf *p,
   struct netbuf *buf;
   struct netconn *conn;
 
-  pcb = pcb; /* Remove warning */
+  LWIP_UNUSED_ARG(pcb);
 
   conn = arg;
   
@@ -115,7 +116,7 @@ recv_tcp(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
   struct netconn *conn;
   u16_t len;
   
-  pcb = pcb; /* Remove warning */
+  LWIP_UNUSED_ARG(pcb);
   
   conn = arg;
 
@@ -147,7 +148,7 @@ poll_tcp(void *arg, struct tcp_pcb *pcb)
 {
   struct netconn *conn;
 
-  pcb = pcb; /* Remove warning */
+  LWIP_UNUSED_ARG(pcb);
   
   conn = arg;
 
@@ -164,7 +165,7 @@ sent_tcp(void *arg, struct tcp_pcb *pcb, u16_t len)
 {
   struct netconn *conn;
 
-  pcb = pcb; /* Remove warning */
+  LWIP_UNUSED_ARG(pcb);
   
   conn = arg;
 
@@ -445,7 +446,7 @@ do_connected(void *arg, struct tcp_pcb *pcb, err_t err)
 {
   struct netconn *conn;
 
-  pcb = pcb; /* Remove warning */
+  LWIP_UNUSED_ARG(pcb);
   
   conn = arg;
 
diff --git a/src/api/sockets.c b/src/api/sockets.c
index 5188dfa8..02afc7da 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -323,6 +323,9 @@ lwip_listen(int s, int backlog)
   struct lwip_socket *sock;
   err_t err;
 
+  /* This does no harm. If debugging is off, backlog is unused. */
+  LWIP_UNUSED_ARG(backlog);
+
   LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d, backlog=%d)\n", s, backlog));
   sock = get_socket(s);
   if (!sock)
diff --git a/src/core/dhcp.c b/src/core/dhcp.c
index 949834eb..a3548208 100644
--- a/src/core/dhcp.c
+++ b/src/core/dhcp.c
@@ -1197,7 +1197,9 @@ static void dhcp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_
   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->len = %"U16_F"\n", p->len));
   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->tot_len = %"U16_F"\n", p->tot_len));
   /* prevent warnings about unused arguments */
-  (void)pcb; (void)addr; (void)port;
+  LWIP_UNUSED_ARG(pcb);
+  LWIP_UNUSED_ARG(addr);
+  LWIP_UNUSED_ARG(port);
   dhcp->p = p;
   /* TODO: check packet length before reading them */
   if (reply_msg->op != DHCP_BOOTREPLY) {
diff --git a/src/core/snmp/msg_in.c b/src/core/snmp/msg_in.c
index 71daffad..d4f82d77 100644
--- a/src/core/snmp/msg_in.c
+++ b/src/core/snmp/msg_in.c
@@ -801,7 +801,7 @@ snmp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr,
   struct udp_hdr *udphdr;
 
   /* suppress unused argument warning */
-  if (arg);
+  LWIP_UNUSED_ARG(arg);
   /* peek in the UDP header (goto IP payload) */
   if(pbuf_header(p, UDP_HLEN)){
     LWIP_ASSERT("Can't move to UDP header", 0);
diff --git a/src/include/lwip/arch.h b/src/include/lwip/arch.h
index 3713bba4..9f9803d8 100644
--- a/src/include/lwip/arch.h
+++ b/src/include/lwip/arch.h
@@ -55,6 +55,10 @@
 #endif /* PACK_STRUCT_FIELD */
 
 
+#ifndef LWIP_UNUSED_ARG
+#define LWIP_UNUSED_ARG(x) (void)x
+#endif /* LWIP_UNUSED_ARG */ 
+
 
 #ifdef LWIP_PROVIDE_ERRNO