diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index da934fc..9fa25b0 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2842,25 +2842,25 @@
 	skb->dev = odev;
 	skb->pkt_type = PACKET_HOST;
 
+	pktgen_finalize_skb(pkt_dev, skb, datalen);
+
 	if (!(pkt_dev->flags & F_UDPCSUM)) {
 		skb->ip_summed = CHECKSUM_NONE;
 	} else if (odev->features & NETIF_F_V4_CSUM) {
 		skb->ip_summed = CHECKSUM_PARTIAL;
 		skb->csum = 0;
-		udp4_hwcsum(skb, udph->source, udph->dest);
+		udp4_hwcsum(skb, iph->saddr, iph->daddr);
 	} else {
-		__wsum csum = udp_csum(skb);
+		__wsum csum = skb_checksum(skb, skb_transport_offset(skb), datalen + 8, 0);
 
 		/* add protocol-dependent pseudo-header */
-		udph->check = csum_tcpudp_magic(udph->source, udph->dest,
+		udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
 						datalen + 8, IPPROTO_UDP, csum);
 
 		if (udph->check == 0)
 			udph->check = CSUM_MANGLED_0;
 	}
 
-	pktgen_finalize_skb(pkt_dev, skb, datalen);
-
 #ifdef CONFIG_XFRM
 	if (!process_ipsec(pkt_dev, skb, protocol))
 		return NULL;
@@ -2976,6 +2976,8 @@
 	skb->dev = odev;
 	skb->pkt_type = PACKET_HOST;
 
+	pktgen_finalize_skb(pkt_dev, skb, datalen);
+
 	if (!(pkt_dev->flags & F_UDPCSUM)) {
 		skb->ip_summed = CHECKSUM_NONE;
 	} else if (odev->features & NETIF_F_V6_CSUM) {
@@ -2984,7 +2986,7 @@
 		skb->csum_offset = offsetof(struct udphdr, check);
 		udph->check = ~csum_ipv6_magic(&iph->saddr, &iph->daddr, udplen, IPPROTO_UDP, 0);
 	} else {
-		__wsum csum = udp_csum(skb);
+		__wsum csum = skb_checksum(skb, skb_transport_offset(skb), udplen, 0);
 
 		/* add protocol-dependent pseudo-header */
 		udph->check = csum_ipv6_magic(&iph->saddr, &iph->daddr, udplen, IPPROTO_UDP, csum);
@@ -2993,8 +2995,6 @@
 			udph->check = CSUM_MANGLED_0;
 	}
 
-	pktgen_finalize_skb(pkt_dev, skb, datalen);
-
 	return skb;
 }