Index: sys/netinet/icmp6.h
===================================================================
--- sys/netinet/icmp6.h
+++ sys/netinet/icmp6.h
@@ -156,6 +156,7 @@
 #define ICMP6_PARAMPROB_HEADER 	 	0	/* erroneous header field */
 #define ICMP6_PARAMPROB_NEXTHEADER	1	/* unrecognized next header */
 #define ICMP6_PARAMPROB_OPTION		2	/* unrecognized option */
+#define ICMP6_PARAMPROB_FRAGHDRCHAIN	3	/* first fragment has incomplete header chain */
 
 #define ICMP6_INFOMSG_MASK		0x80	/* all informational messages */
 
@@ -587,6 +588,7 @@
 	uint64_t icp6errs_paramprob_header;
 	uint64_t icp6errs_paramprob_nextheader;
 	uint64_t icp6errs_paramprob_option;
+	uint64_t icp6errs_paramprob_fraghdrchain;
 	uint64_t icp6errs_redirect; /* we regard redirect as an error here */
 	uint64_t icp6errs_unknown;
 };
@@ -626,6 +628,8 @@
 #define icp6s_oparamprob_nextheader \
 	icp6s_outerrhist.icp6errs_paramprob_nextheader
 #define icp6s_oparamprob_option icp6s_outerrhist.icp6errs_paramprob_option
+#define icp6s_oparamprob_fraghdrchain \
+	icp6s_outerrhist.icp6errs_paramprob_fraghdrchain
 #define icp6s_oredirect icp6s_outerrhist.icp6errs_redirect
 #define icp6s_ounknown icp6s_outerrhist.icp6errs_unknown
 	uint64_t icp6s_pmtuchg;		/* path MTU changes */
Index: sys/netinet6/icmp6.c
===================================================================
--- sys/netinet6/icmp6.c
+++ sys/netinet6/icmp6.c
@@ -210,6 +210,9 @@
 		case ICMP6_PARAMPROB_OPTION:
 			ICMP6STAT_INC(icp6s_oparamprob_option);
 			return;
+		case ICMP6_PARAMPROB_FRAGHDRCHAIN:
+			ICMP6STAT_INC(icp6s_oparamprob_fraghdrchain);
+			return;
 		}
 		break;
 	case ND_REDIRECT:
@@ -535,6 +538,7 @@
 			break;
 		case ICMP6_PARAMPROB_HEADER:
 		case ICMP6_PARAMPROB_OPTION:
+		case ICMP6_PARAMPROB_FRAGHDRCHAIN:
 			code = PRC_PARAMPROB;
 			break;
 		default:
Index: sys/netinet6/in6.h
===================================================================
--- sys/netinet6/in6.h
+++ sys/netinet6/in6.h
@@ -641,7 +641,8 @@
 					 * queue */
 #define	IPV6CTL_MAXFRAGSPERPACKET	53 /* Max fragments per packet */
 #define	IPV6CTL_MAXFRAGBUCKETSIZE	54 /* Max reassembly queues per bucket */
-#define	IPV6CTL_MAXID		55
+#define	IPV6CTL_UNKNOWN_UPPERLAYERHDR	55 /* Allow unknown upper layer headers */
+#define	IPV6CTL_MAXID		56
 #endif /* __BSD_VISIBLE */
 
 /*
Index: usr.bin/netstat/inet6.c
===================================================================
--- usr.bin/netstat/inet6.c
+++ usr.bin/netstat/inet6.c
@@ -1035,6 +1035,8 @@
 	    "{N:/unrecognized next header}\n");
 	p_5(icp6s_oparamprob_option, "\t\t{:bad-option/%ju} "
 	    "{N:/unrecognized option}\n");
+	p_5(icp6s_oparamprob_fraghdrchain, "\t\t{:bad-header-chain/%ju} "
+	    "{N:/incomplete upper layer first fragment}\n");
 	p_5(icp6s_oredirect, "\t\t{:redirects/%ju} "
 	    "{N:/redirect}\n");
 	p_5(icp6s_ounknown, "\t\t{:unknown/%ju} {N:unknown}\n");