diff --git a/sys/netinet/ip_fw2.c b/sys/netinet/ip_fw2.c
index 4793164c9963..807f48d2cef9 100644
--- a/sys/netinet/ip_fw2.c
+++ b/sys/netinet/ip_fw2.c
@@ -87,6 +87,9 @@
 
 #include <netinet/ip6.h>
 #include <netinet/icmp6.h>
+#ifdef INET6
+#include <netinet6/scope6_var.h>
+#endif
 
 #include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */