Index: /trunk/src/VBox/NetworkServices/NAT/pxping_win.c
===================================================================
--- /trunk/src/VBox/NetworkServices/NAT/pxping_win.c	(revision 53365)
+++ /trunk/src/VBox/NetworkServices/NAT/pxping_win.c	(revision 53366)
@@ -193,5 +193,5 @@
 
     bufsize = sizeof(ICMP_ECHO_REPLY) + p->tot_len;
-    pong = (struct pong4 *)malloc(sizeof(*pong) - sizeof(pong->buf) + bufsize);
+    pong = (struct pong4 *)malloc(RT_OFFSETOF(struct pong4, buf) + bufsize);
     if (RT_UNLIKELY(pong == NULL)) {
         goto out;
@@ -470,5 +470,5 @@
 
     bufsize = sizeof(ICMPV6_ECHO_REPLY) + p->tot_len;
-    pong = (struct pong6 *)malloc(sizeof(*pong) - sizeof(pong->buf) + bufsize);
+    pong = (struct pong6 *)malloc(RT_OFFSETOF(struct pong6, buf) + bufsize);
     if (RT_UNLIKELY(pong == NULL)) {
         goto out;