return (__force __wsum)n;
 }
 
+#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
 #endif
 
                                 ip_vs_check_diff(oldport ^ htons(0xFFFF),
                                                  newport, uhdr->check));
        if (!uhdr->check)
-               uhdr->check = -1;
+               uhdr->check = CSUM_MANGLED_0;
 }
 
 static int
                                                cp->protocol,
                                                (*pskb)->csum);
                if (udph->check == 0)
-                       udph->check = -1;
+                       udph->check = CSUM_MANGLED_0;
                IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
                          pp->name, udph->check,
                          (char*)&(udph->check) - (char*)udph);
                                                cp->protocol,
                                                (*pskb)->csum);
                if (udph->check == 0)
-                       udph->check = -1;
+                       udph->check = CSUM_MANGLED_0;
                (*pskb)->ip_summed = CHECKSUM_UNNECESSARY;
        }
        return 1;
 
                                                csum_partial((char *)udph,
                                                             datalen, 0));
                if (!udph->check)
-                       udph->check = -1;
+                       udph->check = CSUM_MANGLED_0;
        } else
                udph->check = nf_proto_csum_update(*pskb,
                                                   htons(oldlen) ^ htons(0xFFFF),
 
                                                  *portptr ^ htons(0xFFFF), newport,
                                                  hdr->check, 0);
                if (!hdr->check)
-                       hdr->check = -1;
+                       hdr->check = CSUM_MANGLED_0;
        }
        *portptr = newport;
        return 1;
 
 
                uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
                if (uh->check == 0)
-                       uh->check = -1;
+                       uh->check = CSUM_MANGLED_0;
        }
 }
 
        uh->check = csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst, up->len,
                                      sk->sk_protocol, csum             );
        if (uh->check == 0)
-               uh->check = -1;
+               uh->check = CSUM_MANGLED_0;
 
 send:
        err = ip_push_pending_frames(sk);
 
                                   &fl->fl6_dst,
                                   total_len, fl->proto, tmp_csum);
 
-       if (tmp_csum == 0 && fl->proto == IPPROTO_UDP)
-               tmp_csum = -1;
+       if (csum == 0 && fl->proto == IPPROTO_UDP)
+               csum = CSUM_MANGLED_0;
 
        if (skb_store_bits(skb, offset, &csum, 2))
                BUG();
 
        uh->check = csum_ipv6_magic(&fl->fl6_src, &fl->fl6_dst,
                                    up->len, fl->proto, csum   );
        if (uh->check == 0)
-               uh->check = -1;
+               uh->check = CSUM_MANGLED_0;
 
        err = ip6_push_pending_frames(sk);
 out: