diff --git a/sys/netinet/ip_fw.h b/sys/netinet/ip_fw.h
--- a/sys/netinet/ip_fw.h
+++ b/sys/netinet/ip_fw.h
@@ -339,7 +339,7 @@
  *
  */
 typedef struct	_ipfw_insn {	/* template for instructions */
-	u_int8_t 	opcode;
+	_Alignas(_Alignof(u_int32_t)) u_int8_t 	opcode;
 	u_int8_t	len;	/* number of 32-bit words */
 #define	F_NOT		0x80
 #define	F_OR		0x40