nskb->ip_summed = skb->ip_summed;
nskb->csum = skb->csum;
#endif
-#if defined(CONFIG_XEN) && LINUX_VERSION_CODE == KERNEL_VERSION(2,6,18)
+#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
/* These fields are copied in skb_clone but not in
* skb_copy or related functions. We need to manually
* copy them over here. */