Index: sys/net/if_pfsync.h
===================================================================
--- sys/net/if_pfsync.h
+++ sys/net/if_pfsync.h
@@ -50,6 +50,7 @@
 #define	_NET_IF_PFSYNC_H_
 
 #define	PFSYNC_VERSION		5
+#define	PFSYNC_REVISION		1
 #define	PFSYNC_DFLTTL		255
 
 #define	PFSYNC_ACT_CLR		0	/* clear all states */
@@ -99,7 +100,7 @@
 
 struct pfsync_header {
 	u_int8_t			version;
-	u_int8_t			_pad;
+	u_int8_t			revision;
 	u_int16_t			len;
 	u_int8_t			pfcksum[PF_MD5_DIGEST_LENGTH];
 } __packed;
@@ -110,8 +111,8 @@
 
 struct pfsync_subheader {
 	u_int8_t			action;
-	u_int8_t			_pad;
-	u_int16_t			count;
+	u_int8_t			size;	/* Structure size in 16-bits. */
+	u_int16_t			count;	/* Number of structures. */
 } __packed;
 
 /*
Index: sys/netpfil/pf/if_pfsync.c
===================================================================
--- sys/netpfil/pf/if_pfsync.c
+++ sys/netpfil/pf/if_pfsync.c
@@ -1547,6 +1547,7 @@
 	offset += sizeof(*ph);
 
 	ph->version = PFSYNC_VERSION;
+	ph->revision = PFSYNC_REVISION;
 	ph->len = htons(sc->sc_len - sizeof(*ip));
 	bcopy(V_pf_status.pf_chksum, ph->pfcksum, PF_MD5_DIGEST_LENGTH);
 
@@ -1577,6 +1578,7 @@
 
 		bzero(subh, sizeof(*subh));
 		subh->action = pfsync_qs[q].action;
+		subh->size = pfsync_qs[q].len >> 1;
 		subh->count = htons(count);
 		V_pfsyncstats.pfsyncs_oacts[pfsync_qs[q].action] += count;
 	}
@@ -1598,6 +1600,7 @@
 
 		bzero(subh, sizeof(*subh));
 		subh->action = PFSYNC_ACT_UPD_REQ;
+		subh->size = sizeof(ur->ur_msg) >> 1;
 		subh->count = htons(count);
 		V_pfsyncstats.pfsyncs_oacts[PFSYNC_ACT_UPD_REQ] += count;
 	}
@@ -1615,6 +1618,7 @@
 
 	bzero(subh, sizeof(*subh));
 	subh->action = PFSYNC_ACT_EOF;
+	subh->size = 0;
 	subh->count = htons(1);
 	V_pfsyncstats.pfsyncs_oacts[PFSYNC_ACT_EOF]++;