diff --git a/components/coap/port/coap_io_socket.c b/components/coap/port/coap_io_socket.c
index eec8cc1..cd63f38 100644
--- a/components/coap/port/coap_io_socket.c
+++ b/components/coap/port/coap_io_socket.c
@@ -251,7 +251,7 @@ coap_network_send(struct coap_context_t *context UNUSED_PARAM,
     (struct coap_endpoint_t *)local_interface;
 
 #ifndef WITH_CONTIKI
-  return sendto(ep->handle.fd, data, datalen, 0, (struct sockaddr*)&dst->addr.sa, sizeof(struct sockaddr));
+  return sendto(ep->handle.fd, data, datalen, 0, &dst->addr.sa, dst->size);
 #else /* WITH_CONTIKI */
   /* FIXME: untested */
   /* FIXME: is there a way to check if send was successful? */
@@ -340,8 +340,6 @@ coap_network_read(coap_endpoint_t *ep, coap_packet_t **packet) {
 #ifdef WITH_POSIX
   #define SOC_APPDATA_LEN 1460
   char *soc_appdata = NULL;
-  struct sockaddr_in soc_srcipaddr;
-  socklen_t soc_srcsize = sizeof(struct sockaddr_in);
 #endif /* WITH_POSIX */
 
   assert(ep);
@@ -360,23 +358,14 @@ coap_network_read(coap_endpoint_t *ep, coap_packet_t **packet) {
 #ifdef WITH_POSIX
   soc_appdata = coap_malloc(SOC_APPDATA_LEN);
   if (soc_appdata){
-	  len = recvfrom(ep->handle.fd, soc_appdata, SOC_APPDATA_LEN, 0, (struct sockaddr *)&soc_srcipaddr, (socklen_t *)&soc_srcsize);
+	  (*packet)->src.size = sizeof((*packet)->src.addr);
+	  len = recvfrom(ep->handle.fd, soc_appdata, SOC_APPDATA_LEN, 0,
+			 &(*packet)->src.addr.sa, &(*packet)->src.size);
 
 	  if (len < 0){
 		  coap_log(LOG_WARNING, "coap_network_read: %s\n", strerror(errno));
 		  goto error;
 	  } else {
-		  /* use getsockname() to get the local port */
-	      (*packet)->dst.size = sizeof((*packet)->dst.addr);
-	      if (getsockname(ep->handle.fd, &(*packet)->dst.addr.sa, &(*packet)->dst.size) < 0) {
-	         coap_log(LOG_DEBUG, "cannot determine local port\n");
-	         goto error;
-	      }
-
-	      /* local interface for IPv4 */
-	      (*packet)->src.size = sizeof((*packet)->src.addr);
-	      memcpy(&(*packet)->src.addr.sa, &soc_srcipaddr, (*packet)->src.size);
-
 	      if (len > coap_get_max_packetlength(*packet)) {
 	         /* FIXME: we might want to send back a response */
 	         warn("discarded oversized packet\n");