Index: /trunk/src/VBox/Devices/Network/slirp/ip_icmpwin.c
===================================================================
--- /trunk/src/VBox/Devices/Network/slirp/ip_icmpwin.c	(revision 53359)
+++ /trunk/src/VBox/Devices/Network/slirp/ip_icmpwin.c	(revision 53360)
@@ -315,5 +315,5 @@
         m_append(pData, m, reqsize, reply->Data);
 
-        icmp->icmp_cksum = in_cksum_skip(m, sizeof(*icmp) + reqsize, sizeof(*ip));
+        icmp->icmp_cksum = in_cksum_skip(m, ip->ip_len, sizeof(*ip));
     }
     else {
@@ -412,5 +412,5 @@
     m_append(pData, m, sizeof(pong->reqicmph), (caddr_t)&pong->reqicmph);
 
-    icmp->icmp_cksum = in_cksum_skip(m, sizeof(*icmp) + reqsize, sizeof(*ip));
+    icmp->icmp_cksum = in_cksum_skip(m, ip->ip_len, sizeof(*ip));
 
     return m;