diff --git a/sys/net/npf/npf.h b/sys/net/npf/npf.h
index 065c862a75a0..e250f6d51305 100644
--- a/sys/net/npf/npf.h
+++ b/sys/net/npf/npf.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: npf.h,v 1.40 2014/05/30 23:26:06 rmind Exp $	*/
+/*	$NetBSD: npf.h,v 1.41 2014/06/25 00:20:06 rmind Exp $	*/
 
 /*-
  * Copyright (c) 2009-2014 The NetBSD Foundation, Inc.
@@ -67,6 +67,8 @@ typedef uint8_t			npf_netmask_t;
 #define	BPF_MW_L4OFF		1
 #define	BPF_MW_L4PROTO		2
 #endif
+/* The number of words used. */
+#define	NPF_BPF_NWORDS		3
 
 #if defined(_KERNEL)
 
diff --git a/sys/net/npf/npf_bpf.c b/sys/net/npf/npf_bpf.c
index 015300d0e69b..2f82d0f15cc9 100644
--- a/sys/net/npf/npf_bpf.c
+++ b/sys/net/npf/npf_bpf.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: npf_bpf.c,v 1.7 2014/06/24 11:31:49 alnsn Exp $	*/
+/*	$NetBSD: npf_bpf.c,v 1.8 2014/06/25 00:20:06 rmind Exp $	*/
 
 /*-
  * Copyright (c) 2009-2013 The NetBSD Foundation, Inc.
@@ -34,11 +34,12 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: npf_bpf.c,v 1.7 2014/06/24 11:31:49 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: npf_bpf.c,v 1.8 2014/06/25 00:20:06 rmind Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
 
+#include <sys/bitops.h>
 #include <sys/mbuf.h>
 #include <net/bpf.h>
 
@@ -59,12 +60,15 @@ static const bpf_copfunc_t npf_bpfcop[] = {
 	[NPF_COP_TABLE]	= npf_cop_table,
 };
 
+#define	BPF_MW_ALLMASK \
+    ((1U << BPF_MW_IPVER) | (1U << BPF_MW_L4OFF) | (1U << BPF_MW_L4PROTO))
+
 void
 npf_bpf_sysinit(void)
 {
 	npf_bpfctx = bpf_create();
-	KASSERT(npf_bpfctx != NULL);
 	bpf_set_cop(npf_bpfctx, npf_bpfcop, __arraycount(npf_bpfcop));
+	bpf_set_extmem(npf_bpfctx, NPF_BPF_NWORDS, BPF_MW_ALLMASK);
 }
 
 void
@@ -73,6 +77,20 @@ npf_bpf_sysfini(void)
 	bpf_destroy(npf_bpfctx);
 }
 
+void
+npf_bpf_prepare(npf_cache_t *npc, nbuf_t *nbuf, bpf_args_t *args, uint32_t *m)
+{
+	const struct mbuf *mbuf = nbuf_head_mbuf(nbuf);
+	const size_t pktlen = m_length(mbuf);
+
+	/* Prepare the arguments for the BPF programs. */
+	args->pkt = (const uint8_t *)mbuf;
+	args->wirelen = pktlen;
+	args->buflen = 0;
+	args->mem = m;
+	args->arg = npc;
+}
+
 int
 npf_bpf_filter(bpf_args_t *args, const void *code, bpfjit_func_t jcode)
 {
diff --git a/sys/net/npf/npf_impl.h b/sys/net/npf/npf_impl.h
index f14bdf2ddfa6..61ee67140d40 100644
--- a/sys/net/npf/npf_impl.h
+++ b/sys/net/npf/npf_impl.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: npf_impl.h,v 1.52 2014/05/30 23:26:06 rmind Exp $	*/
+/*	$NetBSD: npf_impl.h,v 1.53 2014/06/25 00:20:06 rmind Exp $	*/
 
 /*-
  * Copyright (c) 2009-2014 The NetBSD Foundation, Inc.
@@ -223,6 +223,7 @@ bool		npf_return_block(npf_cache_t *, nbuf_t *, const int);
 /* BPF interface. */
 void		npf_bpf_sysinit(void);
 void		npf_bpf_sysfini(void);
+void		npf_bpf_prepare(npf_cache_t *, nbuf_t *, bpf_args_t *, uint32_t *);
 int		npf_bpf_filter(bpf_args_t *, const void *, bpfjit_func_t);
 void *		npf_bpf_compile(void *, size_t);
 bool		npf_bpf_validate(const void *, size_t);
diff --git a/sys/net/npf/npf_ruleset.c b/sys/net/npf/npf_ruleset.c
index 8cab4f04f651..335c0304718c 100644
--- a/sys/net/npf/npf_ruleset.c
+++ b/sys/net/npf/npf_ruleset.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: npf_ruleset.c,v 1.32 2014/06/24 10:53:30 alnsn Exp $	*/
+/*	$NetBSD: npf_ruleset.c,v 1.33 2014/06/25 00:20:06 rmind Exp $	*/
 
 /*-
  * Copyright (c) 2009-2013 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: npf_ruleset.c,v 1.32 2014/06/24 10:53:30 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: npf_ruleset.c,v 1.33 2014/06/25 00:20:06 rmind Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -741,18 +741,18 @@ npf_ruleset_inspect(npf_cache_t *npc, nbuf_t *nbuf,
 	const u_int nitems = rlset->rs_nitems;
 	const u_int ifid = nbuf->nb_ifid;
 	npf_rule_t *final_rl = NULL;
-	const struct mbuf *m;
 	bpf_args_t bc_args;
 	u_int n = 0;
 
-	memset(&bc_args, 0, sizeof(bpf_args_t));
-	m = nbuf_head_mbuf(nbuf);
-	bc_args.pkt = (const uint8_t *)m;
-	bc_args.wirelen = m_length(m);
-	bc_args.arg = npc;
-
 	KASSERT(((di & PFIL_IN) != 0) ^ ((di & PFIL_OUT) != 0));
 
+	/*
+	 * Prepare the external memory store and the arguments for
+	 * the BPF programs to be executed.
+	 */
+	uint32_t bc_words[NPF_BPF_NWORDS];
+	npf_bpf_prepare(npc, nbuf, &bc_args, bc_words);
+
 	while (n < nitems) {
 		npf_rule_t *rl = rlset->rs_rules[n];
 		const u_int skip_to = rl->r_skip_to;
diff --git a/usr.sbin/npf/npftest/libnpftest/npf_bpf_test.c b/usr.sbin/npf/npftest/libnpftest/npf_bpf_test.c
index 5c2780432a34..83ad4f9a0e1f 100644
--- a/usr.sbin/npf/npftest/libnpftest/npf_bpf_test.c
+++ b/usr.sbin/npf/npftest/libnpftest/npf_bpf_test.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: npf_bpf_test.c,v 1.5 2014/06/24 10:53:30 alnsn Exp $	*/
+/*	$NetBSD: npf_bpf_test.c,v 1.6 2014/06/25 00:20:06 rmind Exp $	*/
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -63,6 +63,7 @@ test_bpf_code(void *code, size_t size)
 {
 	ifnet_t *dummy_ifp = npf_test_addif(IFNAME_TEST, false, false);
 	npf_cache_t npc = { .npc_info = 0 };
+	uint32_t memstore[BPF_MEMWORDS];
 	bpf_args_t bc_args;
 	struct mbuf *m;
 	nbuf_t nbuf;
@@ -74,9 +75,10 @@ test_bpf_code(void *code, size_t size)
 	nbuf_init(&nbuf, m, dummy_ifp);
 	npf_cache_all(&npc, &nbuf);
 
-	memset(&bc_args, 0, sizeof(bpf_args_t));
 	bc_args.pkt = (const uint8_t *)m;
-	bc_args.wirelen = m_length(m);
+	bc_args.buflen = m_length(m);
+	bc_args.wirelen = bc_args.buflen;
+	bc_args.mem = memstore;
 	bc_args.arg = &npc;
 
 	ret = npf_bpf_filter(&bc_args, code, NULL);