diff --git a/core/net/packetbuf.c b/core/net/packetbuf.c
index 06f2c0037..82f85377c 100644
--- a/core/net/packetbuf.c
+++ b/core/net/packetbuf.c
@@ -109,7 +109,7 @@ packetbuf_compact(void)
   if(packetbuf_is_reference()) {
     memcpy(&packetbuf[PACKETBUF_HDR_SIZE], packetbuf_reference_ptr(),
 	   packetbuf_datalen());
-  } else if (bufptr > 0) {
+  } else if(bufptr > 0) {
     len = packetbuf_datalen() + PACKETBUF_HDR_SIZE;
     for(i = PACKETBUF_HDR_SIZE; i < len; i++) {
       packetbuf[i] = packetbuf[bufptr + i];
diff --git a/core/net/sicslowpan.c b/core/net/sicslowpan.c
index c0ceb641e..2bb94574f 100644
--- a/core/net/sicslowpan.c
+++ b/core/net/sicslowpan.c
@@ -1648,7 +1648,7 @@ input(void)
     if((frag_size > 0) && (frag_size <= UIP_BUFSIZE)) {
       sicslowpan_len = frag_size;
       reass_tag = frag_tag;
-      timer_set(&reass_timer, SICSLOWPAN_REASS_MAXAGE*CLOCK_SECOND);
+      timer_set(&reass_timer, SICSLOWPAN_REASS_MAXAGE * CLOCK_SECOND / 16);
       PRINTFI("sicslowpan input: INIT FRAGMENTATION (len %d, tag %d)\n",
              sicslowpan_len, reass_tag);
       rimeaddr_copy(&frag_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER));
diff --git a/core/net/tcpip.c b/core/net/tcpip.c
index 018a6a982..4b178a1db 100644
--- a/core/net/tcpip.c
+++ b/core/net/tcpip.c
@@ -373,7 +373,7 @@ eventhandler(process_event_t ev, process_data_t data)
   register struct listenport *l;
 #endif /*UIP_TCP*/
   struct process *p;
-   
+
   switch(ev) {
     case PROCESS_EVENT_EXITED:
       /* This is the event we get if a process has exited. We go through
@@ -471,13 +471,13 @@ eventhandler(process_event_t ev, process_data_t data)
         }*/
 #if !UIP_CONF_ROUTER
         if(data == &uip_ds6_timer_rs &&
-           etimer_expired(&uip_ds6_timer_rs)){
+           etimer_expired(&uip_ds6_timer_rs)) {
           uip_ds6_send_rs();
           tcpip_ipv6_output();
         }
 #endif /* !UIP_CONF_ROUTER */
         if(data == &uip_ds6_timer_periodic &&
-           etimer_expired(&uip_ds6_timer_periodic)){
+           etimer_expired(&uip_ds6_timer_periodic)) {
           uip_ds6_periodic();
           tcpip_ipv6_output();
         }
diff --git a/core/net/uip-icmp6.c b/core/net/uip-icmp6.c
index 4d6ae90b3..59a71013d 100644
--- a/core/net/uip-icmp6.c
+++ b/core/net/uip-icmp6.c
@@ -102,7 +102,7 @@ uip_icmp6_echo_request_input(void)
 
   if(uip_ext_len > 0) {
 #if UIP_CONF_IPV6_RPL
-    if ((temp_ext_len=rpl_invert_header())) {
+    if((temp_ext_len = rpl_invert_header())) {
       /* If there were other extension headers*/
       UIP_FIRST_EXT_BUF->next = UIP_PROTO_ICMP6;
       if (uip_ext_len != temp_ext_len) {
@@ -118,7 +118,7 @@ uip_icmp6_echo_request_input(void)
               (uint8_t *)UIP_ICMP_BUF + UIP_ICMPH_LEN,
               (uip_len - UIP_IPH_LEN - temp_ext_len - UIP_ICMPH_LEN));
       }
-      uip_ext_len=temp_ext_len;
+      uip_ext_len = temp_ext_len;
     } else {
 #endif /* UIP_CONF_IPV6_RPL */
       /* If there were extension headers*/
diff --git a/core/net/uip6.c b/core/net/uip6.c
index e18defdec..af6f442e0 100644
--- a/core/net/uip6.c
+++ b/core/net/uip6.c
@@ -855,7 +855,7 @@ ext_hdr_options_process(void)
       case UIP_EXT_HDR_OPT_RPL:
         PRINTF("Processing RPL option\n");
         if(rpl_verify_header(uip_ext_opt_offset)) {
-          PRINTF("RPL Option Error : Dropping Packet");
+          PRINTF("RPL Option Error: Dropping Packet\n");
           return 1;
         }
         uip_ext_opt_offset += (UIP_EXT_HDR_OPT_RPL_BUF->opt_len) + 2;
@@ -1123,17 +1123,19 @@ uip_process(uint8_t flag)
   if(*uip_next_hdr == UIP_PROTO_HBHO) {
 #if UIP_CONF_IPV6_CHECKS
     uip_ext_bitmap |= UIP_EXT_HDR_BITMAP_HBHO;
-#endif /*UIP_CONF_IPV6_CHECKS*/
+#endif /* UIP_CONF_IPV6_CHECKS */
     switch(ext_hdr_options_process()) {
       case 0:
-        /*continue*/
+        /* continue */
         uip_next_hdr = &UIP_EXT_BUF->next;
         uip_ext_len += (UIP_EXT_BUF->len << 3) + 8;
         break;
       case 1:
-        /*silently discard*/
+	PRINTF("Dropping packet after extension header processing\n");
+        /* silently discard */
         goto drop;
       case 2:
+	PRINTF("Sending error message after extension header processing\n");
         /* send icmp error message (created in ext_hdr_options_process)
          * and discard*/
         goto send;
@@ -1448,6 +1450,11 @@ uip_process(uint8_t flag)
 #if UIP_UDP_CHECKSUMS
   uip_len = uip_len - UIP_IPUDPH_LEN;
   uip_appdata = &uip_buf[UIP_IPUDPH_LEN + UIP_LLH_LEN];
+  /* XXX hack: UDP/IPv6 receivers should drop packets with UDP
+     checksum 0. Here, we explicitly receive UDP packets with checksum
+     0. This is to be able to debug code that for one reason or
+     another miscomputes UDP checksums. The reception of zero UDP
+     checksums should be turned into a configration option. */
   if(UIP_UDP_BUF->udpchksum != 0 && uip_udpchksum() != 0xffff) {
     UIP_STAT(++uip_stat.udp.drop);
     UIP_STAT(++uip_stat.udp.chkerr);
@@ -2211,19 +2218,18 @@ uip_process(uint8_t flag)
   UIP_TCP_BUF->seqno[3] = uip_connr->snd_nxt[3];
 
   UIP_IP_BUF->proto = UIP_PROTO_TCP;
-  
+
   UIP_TCP_BUF->srcport  = uip_connr->lport;
   UIP_TCP_BUF->destport = uip_connr->rport;
 
-
   uip_ipaddr_copy(&UIP_IP_BUF->destipaddr, &uip_connr->ripaddr);
-  uip_ds6_select_src(&UIP_IP_BUF->srcipaddr,&UIP_IP_BUF->destipaddr);
-  PRINTF("Sending TCP packet to");
+  uip_ds6_select_src(&UIP_IP_BUF->srcipaddr, &UIP_IP_BUF->destipaddr);
+  PRINTF("Sending TCP packet to ");
   PRINT6ADDR(&UIP_IP_BUF->destipaddr);
-  PRINTF("from");
+  PRINTF(" from ");
   PRINT6ADDR(&UIP_IP_BUF->srcipaddr);
   PRINTF("\n");
-      
+
   if(uip_connr->tcpstateflags & UIP_STOPPED) {
     /* If the connection has issued uip_stop(), we advertise a zero
        window so that the remote host will stop sending data. */