2_t	ip6ph_len;
+	uint8_t		ip6ph_zero[3];
+	uint8_t		ip6ph_nxt;
+} __aligned(4);
+
+#ifdef INVARIANTS
+/* Aligned size of pseudo-header must equal size of IPv6 header. */
+_Static_assert(sizeof(struct ip6_hdr_pseudo) == 40,
+    "IPv6 pseudo-header alignment failure");
+#endif
+
 struct ip6asfrag;		/* frag6.c */
 TAILQ_HEAD(ip6fraghead, ip6asfrag);