diff --git a/sys/alpha/alpha/db_trace.c b/sys/alpha/alpha/db_trace.c
index c2031687f19f..b269dc0bd6f6 100644
--- a/sys/alpha/alpha/db_trace.c
+++ b/sys/alpha/alpha/db_trace.c
@@ -99,7 +99,7 @@ static struct special_symbol {
 	{ (uintptr_t)&XentSys,		"syscall" },
 	{ (uintptr_t)&XentUna,		"unaligned access fault" },
 	{ (uintptr_t)&XentRestart,	"console restart" },
-	{ NULL }
+	{ 0, NULL }
 };
 
 
@@ -180,7 +180,7 @@ sym_is_trapsymbol(uintptr_t v)
 {
 	int i;
 
-	for (i = 0; special_symbols[i].ss_val != NULL; ++i)
+	for (i = 0; special_symbols[i].ss_val != 0; ++i)
 		if (v == special_symbols[i].ss_val)
 			return 1;
 	return 0;
@@ -339,7 +339,7 @@ db_stack_trace_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, char *m
 		if (sym_is_trapsymbol(symval)) {
 			tf = (struct trapframe *)frame;
 
-			for (i = 0; special_symbols[i].ss_val != NULL; ++i)
+			for (i = 0; special_symbols[i].ss_val != 0; ++i)
 				if (symval == special_symbols[i].ss_val)
 					db_printf("--- %s",
 					    special_symbols[i].ss_note);
diff --git a/sys/alpha/alpha/dump_machdep.c b/sys/alpha/alpha/dump_machdep.c
index 0b5a883287b4..42523d75ddb2 100644
--- a/sys/alpha/alpha/dump_machdep.c
+++ b/sys/alpha/alpha/dump_machdep.c
@@ -88,7 +88,7 @@ dumpsys(struct dumperinfo *di)
 
 	dumplo = di->mediaoffset + di->mediasize - Maxmem * (off_t)PAGE_SIZE;
 	dumplo -= sizeof kdh * 2;
-	i = di->dumper(di->priv, &kdh, NULL, dumplo, sizeof kdh);
+	i = di->dumper(di->priv, &kdh, 0, dumplo, sizeof kdh);
 	if (i)
 		printf("\nDump failed writing header (%d)\n", i);
 	dumplo += sizeof kdh;
@@ -111,7 +111,7 @@ dumpsys(struct dumperinfo *di)
 			printf(" %d", count / (1024 * 1024 / PAGE_SIZE));
 			mb = i;
 		}
-		i = di->dumper(di->priv, va, NULL, dumplo, left * PAGE_SIZE);
+		i = di->dumper(di->priv, va, 0, dumplo, left * PAGE_SIZE);
 		if (i)
 			break;
 		count += left;
@@ -120,10 +120,10 @@ dumpsys(struct dumperinfo *di)
 	}
 	if (i) 
 		printf("\nDump failed writing data (%d)\n", i);
-	i = di->dumper(di->priv, &kdh, NULL, dumplo, sizeof kdh);
+	i = di->dumper(di->priv, &kdh, 0, dumplo, sizeof kdh);
 	if (i)
 		printf("\nDump failed writing trailer (%d)\n", i);
-	di->dumper(di->priv, NULL, NULL, 0, 0);  /* tell them we are done */
+	di->dumper(di->priv, NULL, 0, 0, 0);  /* tell them we are done */
 	printf("\nDump complete\n");
 	return;
 }
diff --git a/sys/alpha/pci/apecs.c b/sys/alpha/pci/apecs.c
index cd9da0427643..a7cce49816fb 100644
--- a/sys/alpha/pci/apecs.c
+++ b/sys/alpha/pci/apecs.c
@@ -292,7 +292,7 @@ apecs_attach(device_t dev)
 	sc->smem_base = APECS_PCI_SPARSE;
 	sc->io_base = APECS_PCI_SIO;
 	sc->cfg0_base = KV(APECS_PCI_CONF);
-	sc->cfg1_base = NULL;
+	sc->cfg1_base = 0;
 
 	set_iointr(alpha_dispatch_intr);
 
diff --git a/sys/dev/firewire/fwohci.c b/sys/dev/firewire/fwohci.c
index 63cbbecda5d5..ba54a7cd9755 100644
--- a/sys/dev/firewire/fwohci.c
+++ b/sys/dev/firewire/fwohci.c
@@ -1314,7 +1314,7 @@ fwohci_tx_enable(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 {
 	int err = 0;
 	int idb, z, i, dmach = 0, ldesc;
-	u_int32_t off = NULL;
+	u_int32_t off = 0;
 	struct fwohcidb_tr *db_tr;
 	struct fwohcidb *db;
 
@@ -1329,7 +1329,7 @@ fwohci_tx_enable(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 			break;
 		}
 	}
-	if(off == NULL){
+	if(off == 0){
 		err = EINVAL;
 		return err;
 	}
@@ -1373,7 +1373,7 @@ fwohci_rx_enable(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 {
 	int err = 0;
 	int idb, z, i, dmach = 0, ldesc;
-	u_int32_t off = NULL;
+	u_int32_t off = 0;
 	struct fwohcidb_tr *db_tr;
 	struct fwohcidb *db;
 
@@ -1390,7 +1390,7 @@ fwohci_rx_enable(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 			}
 		}
 	}
-	if(off == NULL){
+	if(off == 0){
 		err = EINVAL;
 		return err;
 	}
diff --git a/sys/dev/gfb/gfb_pci.c b/sys/dev/gfb/gfb_pci.c
index 4527f0bd2074..d36e2d88d308 100644
--- a/sys/dev/gfb/gfb_pci.c
+++ b/sys/dev/gfb/gfb_pci.c
@@ -136,9 +136,9 @@ pcigfb_attach(device_t dev)
 		adp->va_mem_base = (vm_offset_t)rman_get_virtual(sc->res);
 		adp->va_mem_size = rman_get_end(sc->res) -
 		    rman_get_start(sc->res);
-		adp->va_io_base = NULL;
+		adp->va_io_base = 0;
 		adp->va_io_size = 0;
-		adp->va_crtc_addr = NULL;
+		adp->va_crtc_addr = 0;
 		gfb_device_softcs[sc->model][unit] = sc;
 		sc->gfbc = (struct gfb_conf *)malloc(sizeof(struct gfb_conf),
 		    M_DEVBUF, M_NOWAIT);
diff --git a/sys/dev/mpt/mpt_pci.c b/sys/dev/mpt/mpt_pci.c
index afc06847f936..f0b800349bdb 100644
--- a/sys/dev/mpt/mpt_pci.c
+++ b/sys/dev/mpt/mpt_pci.c
@@ -474,7 +474,7 @@ mpt_dma_mem_alloc(mpt_softc_t *mpt)
 	device_t dev = mpt->dev;
 
 	/* Check if we alreay have allocated the reply memory */
-	if (mpt->reply_phys != NULL) {
+	if (mpt->reply_phys != 0) {
 		return 0;
 	}
 
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
index c09e9d6c7528..63e3fcff59fb 100644
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -359,7 +359,7 @@ stopprofclock(p)
 			p->p_flag |= P_STOPPROF;
 			while (p->p_profthreads != 0)
 				msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
-				    "stopprof", NULL);
+				    "stopprof", 0);
 			p->p_flag &= ~P_STOPPROF;
 		}
 		mtx_lock_spin(&sched_lock);
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index aa6e532c21e7..574b3362427c 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -897,7 +897,7 @@ m_defrag(struct mbuf *m0, int how)
 	if (m_final == NULL)
 		goto nospace;
 
-	if (m_dup_pkthdr(m_final, m0, how) == NULL)
+	if (m_dup_pkthdr(m_final, m0, how) == 0)
 		goto nospace;
 
 	m_new = m_final;
diff --git a/sys/netinet/ip_fastfwd.c b/sys/netinet/ip_fastfwd.c
index 667a04c2281f..404171252b93 100644
--- a/sys/netinet/ip_fastfwd.c
+++ b/sys/netinet/ip_fastfwd.c
@@ -463,7 +463,7 @@ ip_fastforward(struct mbuf *m)
 	if (!ipstealth) {
 #endif
 	if (ip->ip_ttl <= IPTTLDEC) {
-		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, NULL, NULL);
+		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, NULL);
 		return 1;
 	}
 
@@ -503,7 +503,7 @@ ip_fastforward(struct mbuf *m)
 	} else {
 		ipstat.ips_noroute++;
 		ipstat.ips_cantforward++;
-		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
+		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, NULL);
 		if (ro.ro_rt)
 			RTFREE(ro.ro_rt);
 		return 1;
@@ -707,8 +707,7 @@ ip_fastforward(struct mbuf *m)
 		} else {
 			ipstat.ips_noroute++;
 			ipstat.ips_cantforward++;
-			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST,
-				NULL, NULL);
+			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, NULL);
 			if (ro.ro_rt)
 				RTFREE(ro.ro_rt);
 			return 1;
@@ -750,7 +749,7 @@ ip_fastforward(struct mbuf *m)
 		 */
 		if (ip->ip_off & IP_DF) {
 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG,
-				NULL, ifp);
+				0, ifp);
 			ipstat.ips_cantfrag++;
 			RTFREE(ro.ro_rt);
 			return 1;
diff --git a/sys/netinet6/in6_src.c b/sys/netinet6/in6_src.c
index 88ace1cc6cac..ab513a836b48 100644
--- a/sys/netinet6/in6_src.c
+++ b/sys/netinet6/in6_src.c
@@ -640,7 +640,7 @@ in6_selectroute(dstsock, opts, mopts, ro, retifp, retrt, clone)
 				rtalloc((struct route *)ro);
 			} else {
 				ro->ro_rt = rtalloc1(&((struct route *)ro)
-						     ->ro_dst, NULL, 0UL);
+						     ->ro_dst, 0, 0UL);
 				if (ro->ro_rt)
 					RT_UNLOCK(ro->ro_rt);
 			}
diff --git a/sys/netinet6/ip6_mroute.c b/sys/netinet6/ip6_mroute.c
index a68237ea9113..95872b86dc66 100644
--- a/sys/netinet6/ip6_mroute.c
+++ b/sys/netinet6/ip6_mroute.c
@@ -1857,7 +1857,7 @@ pim6_input(mp, offp, proto)
 #endif
 
 		rc = if_simloop(mif6table[reg_mif_num].m6_ifp, m,
-				dst.sin6_family, NULL);
+				dst.sin6_family, 0);
 
 		/* prepare the register head to send to the mrouting daemon */
 		m = mcp;
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index 99addae58537..55dbd031a770 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -1481,10 +1481,10 @@ ip6_ctloutput(so, sopt)
 				struct mbuf *m;
 
 				error = soopt_getm(sopt, &m); /* XXX */
-				if (error != NULL)
+				if (error != 0)
 					break;
 				error = soopt_mcopyin(sopt, m); /* XXX */
-				if (error != NULL)
+				if (error != 0)
 					break;
 				error = ip6_pcbopts(&in6p->in6p_outputopts,
 						    m, so, sopt);
@@ -3405,7 +3405,7 @@ ip6_mloopback(ifp, m, dst)
 	in6_clearscope(&ip6->ip6_src);
 	in6_clearscope(&ip6->ip6_dst);
 
-	(void)if_simloop(ifp, copym, dst->sin6_family, NULL);
+	(void)if_simloop(ifp, copym, dst->sin6_family, 0);
 }
 
 /*
diff --git a/sys/pci/if_rl.c b/sys/pci/if_rl.c
index 921d047355c6..1e3863fad18d 100644
--- a/sys/pci/if_rl.c
+++ b/sys/pci/if_rl.c
@@ -170,7 +170,7 @@ static struct rl_type rl_devs[] = {
 		"LevelOne FPC-0106TX" },
 	{ EDIMAX_VENDORID, EDIMAX_DEVICEID_EP4103DL, RL_8139,
 		"Edimax EP-4103DL CardBus" },
-	{ 0, 0, NULL }
+	{ 0, 0, 0, NULL }
 };
 
 static int rl_probe		(device_t);
diff --git a/sys/sys/umtx.h b/sys/sys/umtx.h
index 7b6b3f4fa2b2..2098248d5ac2 100644
--- a/sys/sys/umtx.h
+++ b/sys/sys/umtx.h
@@ -34,7 +34,7 @@
  * See pthread_*
  */
 
-#define	UMTX_UNOWNED	NULL
+#define	UMTX_UNOWNED	0x0
 #define	UMTX_CONTESTED	0x1