diff --git a/sys/netinet/icmp6.h b/sys/netinet/icmp6.h
--- a/sys/netinet/icmp6.h
+++ b/sys/netinet/icmp6.h
@@ -717,8 +717,7 @@
 #define icmp6_ifstat_inc(ifp, tag) \
 do {								\
 	if (ifp)						\
-		counter_u64_add(((struct in6_ifextra *)		\
-		    ((ifp)->if_inet6))->icmp6_ifstat[		\
+		counter_u64_add((ifp)->if_inet6->icmp6_ifstat[	\
 		    offsetof(struct icmp6_ifstat, tag) / sizeof(uint64_t)], 1);\
 } while (/*CONSTCOND*/ 0)
 
diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -2610,14 +2610,8 @@
 	ext = (struct in6_ifextra *)malloc(sizeof(*ext), M_IFADDR, M_WAITOK);
 	bzero(ext, sizeof(*ext));
 
-	ext->in6_ifstat = malloc(sizeof(counter_u64_t) *
-	    sizeof(struct in6_ifstat) / sizeof(uint64_t), M_IFADDR, M_WAITOK);
 	COUNTER_ARRAY_ALLOC(ext->in6_ifstat,
 	    sizeof(struct in6_ifstat) / sizeof(uint64_t), M_WAITOK);
-
-	ext->icmp6_ifstat = malloc(sizeof(counter_u64_t) *
-	    sizeof(struct icmp6_ifstat) / sizeof(uint64_t), M_IFADDR,
-	    M_WAITOK);
 	COUNTER_ARRAY_ALLOC(ext->icmp6_ifstat,
 	    sizeof(struct icmp6_ifstat) / sizeof(uint64_t), M_WAITOK);
 
diff --git a/sys/netinet6/in6_ifattach.c b/sys/netinet6/in6_ifattach.c
--- a/sys/netinet6/in6_ifattach.c
+++ b/sys/netinet6/in6_ifattach.c
@@ -922,10 +922,8 @@
 	lltable_free(ext->lltable);
 	COUNTER_ARRAY_FREE(ext->in6_ifstat,
 	    sizeof(struct in6_ifstat) / sizeof(uint64_t));
-	free(ext->in6_ifstat, M_IFADDR);
 	COUNTER_ARRAY_FREE(ext->icmp6_ifstat,
 	    sizeof(struct icmp6_ifstat) / sizeof(uint64_t));
-	free(ext->icmp6_ifstat, M_IFADDR);
 	free(ext, M_IFADDR);
 }
 EVENTHANDLER_DEFINE(ifnet_departure_event, in6_ifdeparture, NULL,
diff --git a/sys/netinet6/in6_var.h b/sys/netinet6/in6_var.h
--- a/sys/netinet6/in6_var.h
+++ b/sys/netinet6/in6_var.h
@@ -93,25 +93,6 @@
 	u_int32_t ia6t_pltime;	/* prefix lifetime */
 };
 
-struct nd_ifinfo;
-struct scope6_id;
-struct lltable;
-struct mld_ifsoftc;
-struct in6_multi;
-
-struct in6_ifextra {
-	counter_u64_t *in6_ifstat;
-	counter_u64_t *icmp6_ifstat;
-	struct nd_ifinfo *nd_ifinfo;
-	struct scope6_id *scope6_id;
-	struct lltable *lltable;
-	struct mld_ifsoftc *mld_ifinfo;
-	u_int dad_failures;	/* DAD failures when using RFC 7217 stable addresses */
-};
-
-#define	LLTABLE6(ifp)	((ifp)->if_inet6->lltable)
-#define	DAD_FAILURES(ifp)	((ifp)->if_inet6->dad_failures)
-
 #ifdef _KERNEL
 
 SLIST_HEAD(in6_multi_head, in6_multi);
@@ -507,6 +488,23 @@
 #endif
 
 #ifdef _KERNEL
+/*
+ * Structure pointed at by ifp->if_inet6.
+ */
+struct in6_ifextra {
+	counter_u64_t in6_ifstat[sizeof(struct in6_ifstat) / sizeof(uint64_t)];
+	counter_u64_t icmp6_ifstat[sizeof(struct icmp6_ifstat) /
+				   sizeof(uint64_t)];
+	struct nd_ifinfo *nd_ifinfo;
+	struct scope6_id *scope6_id;
+	struct lltable *lltable;
+	struct mld_ifsoftc *mld_ifinfo;
+	u_int dad_failures;	/* DAD failures when using RFC 7217 stable addresses */
+};
+
+#define	LLTABLE6(ifp)	((ifp)->if_inet6->lltable)
+#define	DAD_FAILURES(ifp)	((ifp)->if_inet6->dad_failures)
+
 VNET_DECLARE(struct in6_ifaddrhead, in6_ifaddrhead);
 VNET_DECLARE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
 VNET_DECLARE(u_long, in6_ifaddrhmask);