diff --git a/hw/e1000.c b/hw/e1000.c
index 1a14051629..d81d9bea29 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -279,26 +279,18 @@ flash_eerd_read(E1000State *s, int x)
            E1000_EEPROM_RW_REG_DONE | r;
 }
 
-static unsigned int
-do_cksum(uint8_t *dp, uint8_t *de)
-{
-    unsigned int bsum[2] = {0, 0}, i, sum;
-
-    for (i = 1; dp < de; bsum[i^=1] += *dp++)
-        ;
-    sum = (bsum[0] << 8) + bsum[1];
-    sum = (sum >> 16) + (sum & 0xffff);
-    return ~(sum + (sum >> 16));
-}
-
 static void
 putsum(uint8_t *data, uint32_t n, uint32_t sloc, uint32_t css, uint32_t cse)
 {
+    uint32_t sum;
+
     if (cse && cse < n)
         n = cse + 1;
-    if (sloc < n-1)
+    if (sloc < n-1) {
+        sum = net_checksum_add(n-css, data+css);
         cpu_to_be16wu((uint16_t *)(data + sloc),
-                      do_cksum(data + css, data + n));
+                      net_checksum_finish(sum));
+    }
 }
 
 static void