diff --git a/sys/netinet6/ip6_var.h b/sys/netinet6/ip6_var.h
index bc409780fee..e538afd9399 100644
--- a/sys/netinet6/ip6_var.h
+++ b/sys/netinet6/ip6_var.h
@@ -346,6 +346,7 @@ extern struct	pr_usrreqs rip6_usrreqs;
 struct sockopt;
 
 struct inpcb;
+struct ucred;
 
 int	icmp6_ctloutput(struct socket *, struct sockopt *sopt);