diff --git a/CHANGELOG b/CHANGELOG
index c6690a30..15342e82 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -68,6 +68,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2009-02-16 Simon Goldschmidt
+  * sockets.h/.c, api_*.h/.c: fixed arguments of socket functions to match the standard;
+    converted size argument of netconn_write to 'size_t'
+
   2009-02-16 Simon Goldschmidt
   * tcp.h, tcp.c: fixed bug #24440: TCP connection close problem on 64-bit host
     by moving accept callback function pointer to TCP_PCB_COMMON
diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index 22b65a31..75aa9b53 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -459,7 +459,7 @@ netconn_send(struct netconn *conn, struct netbuf *buf)
  * @return ERR_OK if data was sent, any other err_t on error
  */
 err_t
-netconn_write(struct netconn *conn, const void *dataptr, int size, u8_t apiflags)
+netconn_write(struct netconn *conn, const void *dataptr, size_t size, u8_t apiflags)
 {
   struct api_msg msg;
 
diff --git a/src/api/api_msg.c b/src/api/api_msg.c
index 4bb4e2c2..5a1eb086 100644
--- a/src/api/api_msg.c
+++ b/src/api/api_msg.c
@@ -948,17 +948,19 @@ do_writemore(struct netconn *conn)
   void *dataptr;
   u16_t len, available;
   u8_t write_finished = 0;
+  size_t diff;
 
   LWIP_ASSERT("conn->state == NETCONN_WRITE", (conn->state == NETCONN_WRITE));
 
   dataptr = (u8_t*)conn->write_msg->msg.w.dataptr + conn->write_offset;
-  if (conn->write_msg->msg.w.len - conn->write_offset > 0xffff) { /* max_u16_t */
+  diff = conn->write_msg->msg.w.len - conn->write_offset;
+  if (diff > 0xffffUL) { /* max_u16_t */
     len = 0xffff;
 #if LWIP_TCPIP_CORE_LOCKING
     conn->write_delayed = 1;
 #endif
   } else {
-    len = conn->write_msg->msg.w.len - conn->write_offset;
+    len = (u16_t)diff;
   }
   available = tcp_sndbuf(conn->pcb.tcp);
   if (available < len) {
@@ -1035,6 +1037,8 @@ do_write(struct api_msg_msg *msg)
 #if LWIP_TCP
       msg->conn->state = NETCONN_WRITE;
       /* set all the variables used by do_writemore */
+      LWIP_ASSERT("already writing", msg->conn->write_msg == NULL &&
+        msg->conn->write_offset == 0);
       msg->conn->write_msg = msg;
       msg->conn->write_offset = 0;
 #if LWIP_TCPIP_CORE_LOCKING
diff --git a/src/api/sockets.c b/src/api/sockets.c
index 2dade4a5..7be1b2f4 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -326,7 +326,7 @@ lwip_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
 }
 
 int
-lwip_bind(int s, struct sockaddr *name, socklen_t namelen)
+lwip_bind(int s, const struct sockaddr *name, socklen_t namelen)
 {
   struct lwip_socket *sock;
   struct ip_addr local_addr;
@@ -338,11 +338,11 @@ lwip_bind(int s, struct sockaddr *name, socklen_t namelen)
     return -1;
 
   LWIP_ERROR("lwip_bind: invalid address", ((namelen == sizeof(struct sockaddr_in)) &&
-             ((((struct sockaddr_in *)name)->sin_family) == AF_INET)),
+             ((((const struct sockaddr_in *)name)->sin_family) == AF_INET)),
              sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
 
-  local_addr.addr = ((struct sockaddr_in *)name)->sin_addr.s_addr;
-  local_port = ((struct sockaddr_in *)name)->sin_port;
+  local_addr.addr = ((const struct sockaddr_in *)name)->sin_addr.s_addr;
+  local_port = ((const struct sockaddr_in *)name)->sin_port;
 
   LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d, addr=", s));
   ip_addr_debug_print(SOCKETS_DEBUG, &local_addr);
@@ -398,18 +398,18 @@ lwip_connect(int s, const struct sockaddr *name, socklen_t namelen)
     return -1;
 
   LWIP_ERROR("lwip_connect: invalid address", ((namelen == sizeof(struct sockaddr_in)) &&
-             ((((struct sockaddr_in *)name)->sin_family) == AF_INET)),
+             ((((const struct sockaddr_in *)name)->sin_family) == AF_INET)),
              sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
 
-  if (((struct sockaddr_in *)name)->sin_family == AF_UNSPEC) {
+  if (((const struct sockaddr_in *)name)->sin_family == AF_UNSPEC) {
     LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
     err = netconn_disconnect(sock->conn);
   } else {
     struct ip_addr remote_addr;
     u16_t remote_port;
 
-    remote_addr.addr = ((struct sockaddr_in *)name)->sin_addr.s_addr;
-    remote_port = ((struct sockaddr_in *)name)->sin_port;
+    remote_addr.addr = ((const struct sockaddr_in *)name)->sin_addr.s_addr;
+    remote_port = ((const struct sockaddr_in *)name)->sin_port;
 
     LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
     ip_addr_debug_print(SOCKETS_DEBUG, &remote_addr);
@@ -470,7 +470,7 @@ lwip_listen(int s, int backlog)
 }
 
 int
-lwip_recvfrom(int s, void *mem, int len, unsigned int flags,
+lwip_recvfrom(int s, void *mem, size_t len, int flags,
         struct sockaddr *from, socklen_t *fromlen)
 {
   struct lwip_socket *sock;
@@ -519,7 +519,7 @@ lwip_recvfrom(int s, void *mem, int len, unsigned int flags,
     if (len > buflen) {
       copylen = buflen;
     } else {
-      copylen = len;
+      copylen = (u16_t)len;
     }
 
     /* copy the contents of the received buffer into
@@ -529,6 +529,7 @@ lwip_recvfrom(int s, void *mem, int len, unsigned int flags,
     off += copylen;
 
     if (netconn_type(sock->conn) == NETCONN_TCP) {
+      LWIP_ASSERT("invalid copylen, len would underflow", len >= copylen);
       len -= copylen;
       if ( (len <= 0) || (buf->p->flags & PBUF_FLAG_PUSH) || !sock->rcvevent || ((flags & MSG_PEEK)!=0)) {
         done = 1;
@@ -607,19 +608,19 @@ lwip_recvfrom(int s, void *mem, int len, unsigned int flags,
 }
 
 int
-lwip_read(int s, void *mem, int len)
+lwip_read(int s, void *mem, size_t len)
 {
   return lwip_recvfrom(s, mem, len, 0, NULL, NULL);
 }
 
 int
-lwip_recv(int s, void *mem, int len, unsigned int flags)
+lwip_recv(int s, void *mem, size_t len, int flags)
 {
   return lwip_recvfrom(s, mem, len, flags, NULL, NULL);
 }
 
 int
-lwip_send(int s, const void *data, int size, unsigned int flags)
+lwip_send(int s, const void *data, size_t size, int flags)
 {
   struct lwip_socket *sock;
   err_t err;
@@ -631,7 +632,7 @@ lwip_send(int s, const void *data, int size, unsigned int flags)
   if (!sock)
     return -1;
 
-  if (sock->conn->type!=NETCONN_TCP) {
+  if (sock->conn->type != NETCONN_TCP) {
 #if (LWIP_UDP || LWIP_RAW)
     return lwip_sendto(s, data, size, flags, NULL, 0);
 #else
@@ -644,16 +645,17 @@ lwip_send(int s, const void *data, int size, unsigned int flags)
 
   LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d) err=%d size=%d\n", s, err, size));
   sock_set_errno(sock, err_to_errno(err));
-  return (err==ERR_OK?size:-1);
+  return (err == ERR_OK ? (int)size : -1);
 }
 
 int
-lwip_sendto(int s, const void *data, int size, unsigned int flags,
-       struct sockaddr *to, socklen_t tolen)
+lwip_sendto(int s, const void *data, size_t size, int flags,
+       const struct sockaddr *to, socklen_t tolen)
 {
   struct lwip_socket *sock;
   struct ip_addr remote_addr;
   int err;
+  u16_t short_size;
 #if !LWIP_TCPIP_CORE_LOCKING
   struct netbuf buf;
   u16_t remote_port;
@@ -663,7 +665,7 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
   if (!sock)
     return -1;
 
-  if (sock->conn->type==NETCONN_TCP) {
+  if (sock->conn->type == NETCONN_TCP) {
 #if LWIP_TCP
     return lwip_send(s, data, size, flags);
 #else
@@ -672,11 +674,11 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
 #endif /* LWIP_TCP */
   }
 
-  LWIP_ASSERT("lwip_sendto: size must fit in u16_t",
-              ((size >= 0) && (size <= 0xffff)));
+  LWIP_ASSERT("lwip_sendto: size must fit in u16_t", size <= 0xffff);
+  short_size = (u16_t)size;
   LWIP_ERROR("lwip_sendto: invalid address", (((to == NULL) && (tolen == 0)) ||
              ((tolen == sizeof(struct sockaddr_in)) &&
-             ((((struct sockaddr_in *)to)->sin_family) == AF_INET))),
+             ((((const struct sockaddr_in *)to)->sin_family) == AF_INET))),
              sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
 
 #if LWIP_TCPIP_CORE_LOCKING
@@ -688,15 +690,15 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
       err = ERR_MEM;
     } else {
       p->payload = (void*)data;
-      p->len = p->tot_len = size;
+      p->len = p->tot_len = short_size;
       
-      remote_addr.addr = ((struct sockaddr_in *)to)->sin_addr.s_addr;
+      remote_addr.addr = ((const struct sockaddr_in *)to)->sin_addr.s_addr;
       
       LOCK_TCPIP_CORE();
       if (sock->conn->type==NETCONN_RAW) {
         err = sock->conn->err = raw_sendto(sock->conn->pcb.raw, p, &remote_addr);
       } else {
-        err = sock->conn->err = udp_sendto(sock->conn->pcb.udp, p, &remote_addr, ntohs(((struct sockaddr_in *)to)->sin_port));
+        err = sock->conn->err = udp_sendto(sock->conn->pcb.udp, p, &remote_addr, ntohs(((const struct sockaddr_in *)to)->sin_port));
       }
       UNLOCK_TCPIP_CORE();
       
@@ -707,8 +709,8 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
   /* initialize a buffer */
   buf.p = buf.ptr = NULL;
   if (to) {
-    remote_addr.addr = ((struct sockaddr_in *)to)->sin_addr.s_addr;
-    remote_port      = ntohs(((struct sockaddr_in *)to)->sin_port);
+    remote_addr.addr = ((const struct sockaddr_in *)to)->sin_addr.s_addr;
+    remote_port      = ntohs(((const struct sockaddr_in *)to)->sin_port);
     buf.addr         = &remote_addr;
     buf.port         = remote_port;
   } else {
@@ -718,13 +720,13 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
     buf.port         = 0;
   }
 
-  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_sendto(%d, data=%p, size=%d, flags=0x%x to=",
-              s, data, size, flags));
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_sendto(%d, data=%p, short_size=%d, flags=0x%x to=",
+              s, data, short_size, flags));
   ip_addr_debug_print(SOCKETS_DEBUG, &remote_addr);
   LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%u\n", remote_port));
     
   /* make the buffer point to the data that should be sent */
-  if ((err = netbuf_ref(&buf, data, size)) == ERR_OK) {
+  if ((err = netbuf_ref(&buf, data, short_size)) == ERR_OK) {
     /* send the data */
     err = netconn_send(sock->conn, &buf);
   }
@@ -735,7 +737,7 @@ lwip_sendto(int s, const void *data, int size, unsigned int flags,
   }
 #endif /* LWIP_TCPIP_CORE_LOCKING */
   sock_set_errno(sock, err_to_errno(err));
-  return (err==ERR_OK?size:-1);
+  return (err == ERR_OK ? short_size : -1);
 }
 
 int
@@ -791,7 +793,7 @@ lwip_socket(int domain, int type, int protocol)
 }
 
 int
-lwip_write(int s, const void *data, int size)
+lwip_write(int s, const void *data, size_t size)
 {
   return lwip_send(s, data, size, 0);
 }
diff --git a/src/core/snmp/mib2.c b/src/core/snmp/mib2.c
index c5c2f362..33eeee66 100644
--- a/src/core/snmp/mib2.c
+++ b/src/core/snmp/mib2.c
@@ -2205,10 +2205,10 @@ system_get_value(struct obj_def *od, u16_t len, void *value)
   switch (id)
   {
     case 1: /* sysDescr */
-      ocstrncpy(value,sysdescr_ptr,len);
+      ocstrncpy(value,sysdescr_ptr, len);
       break;
     case 2: /* sysObjectID */
-      objectidncpy((s32_t*)value,(s32_t*)sysobjid.id,len / sizeof(s32_t));
+      objectidncpy((s32_t*)value, (s32_t*)sysobjid.id, (u8_t)(len / sizeof(s32_t)));
       break;
     case 3: /* sysUpTime */
       {
@@ -2606,7 +2606,7 @@ ifentry_get_value(struct obj_def *od, u16_t len, void *value)
       }
       break;
     case 22: /* ifSpecific */
-      objectidncpy((s32_t*)value,(s32_t*)ifspecific.id,len / sizeof(s32_t));
+      objectidncpy((s32_t*)value, (s32_t*)ifspecific.id, (u8_t)(len / sizeof(s32_t)));
       break;
   };
 }
@@ -3342,7 +3342,7 @@ ip_rteentry_get_value(struct obj_def *od, u16_t len, void *value)
         }
         break;
       case 13: /* ipRouteInfo */
-        objectidncpy((s32_t*)value,(s32_t*)iprouteinfo.id,len / sizeof(s32_t));
+        objectidncpy((s32_t*)value, (s32_t*)iprouteinfo.id, (u8_t)(len / sizeof(s32_t)));
         break;
     }
   }
diff --git a/src/include/lwip/api.h b/src/include/lwip/api.h
index 31d767f2..8a116597 100644
--- a/src/include/lwip/api.h
+++ b/src/include/lwip/api.h
@@ -141,9 +141,11 @@ struct netconn {
   /** TCP: when data passed to netconn_write doesn't fit into the send buffer,
       this temporarily stores the message. */
   struct api_msg_msg *write_msg;
+#if LWIP_TCP
   /** TCP: when data passed to netconn_write doesn't fit into the send buffer,
       this temporarily stores how much is already sent. */
-  int write_offset;
+  size_t write_offset;
+#endif /* LWIP_TCP */
 #if LWIP_TCPIP_CORE_LOCKING
   /** TCP: when data passed to netconn_write doesn't fit into the send buffer,
       this temporarily stores whether to wake up the original application task
@@ -191,7 +193,7 @@ err_t             netconn_sendto  (struct netconn *conn,
 err_t             netconn_send    (struct netconn *conn,
                                    struct netbuf *buf);
 err_t             netconn_write   (struct netconn *conn,
-                                   const void *dataptr, int size,
+                                   const void *dataptr, size_t size,
                                    u8_t apiflags);
 err_t             netconn_close   (struct netconn *conn);
 
diff --git a/src/include/lwip/api_msg.h b/src/include/lwip/api_msg.h
index 4c9b48ef..c682222f 100644
--- a/src/include/lwip/api_msg.h
+++ b/src/include/lwip/api_msg.h
@@ -78,7 +78,7 @@ struct api_msg_msg {
     /** used for do_write */
     struct {
       const void *dataptr;
-      int len;
+      size_t len;
       u8_t apiflags;
     } w;
     /** used ofr do_recv */
diff --git a/src/include/lwip/sockets.h b/src/include/lwip/sockets.h
index 46ad4748..994c2421 100644
--- a/src/include/lwip/sockets.h
+++ b/src/include/lwip/sockets.h
@@ -297,7 +297,7 @@ struct timeval {
 void lwip_socket_init(void);
 
 int lwip_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
-int lwip_bind(int s, struct sockaddr *name, socklen_t namelen);
+int lwip_bind(int s, const struct sockaddr *name, socklen_t namelen);
 int lwip_shutdown(int s, int how);
 int lwip_getpeername (int s, struct sockaddr *name, socklen_t *namelen);
 int lwip_getsockname (int s, struct sockaddr *name, socklen_t *namelen);
@@ -306,15 +306,15 @@ int lwip_setsockopt (int s, int level, int optname, const void *optval, socklen_
 int lwip_close(int s);
 int lwip_connect(int s, const struct sockaddr *name, socklen_t namelen);
 int lwip_listen(int s, int backlog);
-int lwip_recv(int s, void *mem, int len, unsigned int flags);
-int lwip_read(int s, void *mem, int len);
-int lwip_recvfrom(int s, void *mem, int len, unsigned int flags,
+int lwip_recv(int s, void *mem, size_t len, int flags);
+int lwip_read(int s, void *mem, size_t len);
+int lwip_recvfrom(int s, void *mem, size_t len, int flags,
       struct sockaddr *from, socklen_t *fromlen);
-int lwip_send(int s, const void *dataptr, int size, unsigned int flags);
-int lwip_sendto(int s, const void *dataptr, int size, unsigned int flags,
-    struct sockaddr *to, socklen_t tolen);
+int lwip_send(int s, const void *dataptr, size_t size, int flags);
+int lwip_sendto(int s, const void *dataptr, size_t size, int flags,
+    const struct sockaddr *to, socklen_t tolen);
 int lwip_socket(int domain, int type, int protocol);
-int lwip_write(int s, const void *dataptr, int size);
+int lwip_write(int s, const void *dataptr, size_t size);
 int lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
                 struct timeval *timeout);
 int lwip_ioctl(int s, long cmd, void *argp);