diff --git a/src/core/inet.c b/src/core/inet.c
index d68f53ae..1dd3dd0d 100644
--- a/src/core/inet.c
+++ b/src/core/inet.c
@@ -53,14 +53,19 @@ lwip_chksum(void *dataptr, int len)
 {
   u32_t acc;
     
+  DEBUGF(INET_DEBUG, ("lwip_chksum(%p, %d)\n", dataptr, len));
   for(acc = 0; len > 1; len -= 2) {
-    acc = acc + *((u16_t *)dataptr)++;
+//    acc = acc + *((u16_t *)dataptr)++;
+    acc += *(u16_t *)dataptr;
+    dataptr = (void *)((u16_t *)dataptr + 1);
   }
 
   /* add up any odd byte */
   if(len == 1) {
     acc += htons((u16_t)((*(u8_t *)dataptr) & 0xff) << 8);
     DEBUGF(INET_DEBUG, ("inet: chksum: odd byte %d\n", *(u8_t *)dataptr));
+  } else {
+    DEBUGF(INET_DEBUG, ("inet: chksum: no odd byte\n"));
   }
   acc = (acc >> 16) + (acc & 0xffffUL);
 
@@ -87,8 +92,11 @@ inet_chksum_pseudo(struct pbuf *p,
 
   acc = 0;
   swapped = 0;
+  /* iterate through all pbuf in chain */
   for(q = p; q != NULL; q = q->next) {    
+    DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n", q, q->next));
     acc += lwip_chksum(q->payload, q->len);
+    //DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%lx \n", acc));
     while(acc >> 16) {
       acc = (acc & 0xffffUL) + (acc >> 16);
     }
@@ -96,6 +104,7 @@ inet_chksum_pseudo(struct pbuf *p,
       swapped = 1 - swapped;
       acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
     }
+    //DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%lx \n", acc));
   }
 
   if(swapped) {
@@ -111,6 +120,7 @@ inet_chksum_pseudo(struct pbuf *p,
   while(acc >> 16) {
     acc = (acc & 0xffffUL) + (acc >> 16);
   }    
+  DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%lx\n", acc));
   return ~(acc & 0xffffUL);
 }
 /*-----------------------------------------------------------------------------------*/