diff --git a/ipv6.c b/ipv6.c
index 371d9e1..d188e47 100644
--- a/ipv6.c
+++ b/ipv6.c
@@ -125,8 +125,8 @@
   out[pos].iov_len = sizeof(struct iphdr);
 
   // Calculate the pseudo-header checksum.
-  old_sum = ipv6_pseudo_header_checksum(0, ip6, len_left);
-  new_sum = ipv4_pseudo_header_checksum(0, ip_targ, len_left);
+  old_sum = ipv6_pseudo_header_checksum(ip6, len_left, protocol);
+  new_sum = ipv4_pseudo_header_checksum(ip_targ, len_left);
 
   // does not support IPv6 extension headers, this will drop any packet with them
   if (protocol == IPPROTO_ICMP) {