diff --git a/sys/kern/kern_dump.c b/sys/kern/kern_dump.c
index 1fd2fdd3ace5..c82272f09f71 100644
--- a/sys/kern/kern_dump.c
+++ b/sys/kern/kern_dump.c
@@ -174,7 +174,7 @@ dumpsys_cb_dumpdata(struct dump_pa *mdp, int seqnr, void *arg)
 
 	error = 0;	/* catch case in which chunk size is 0 */
 	counter = 0;	/* Update twiddle every 16MB */
-	va = 0;
+	va = NULL;
 	pgs = mdp->pa_size / PAGE_SIZE;
 	pa = mdp->pa_start;
 	maxdumppgs = min(di->maxiosize / PAGE_SIZE, MAXDUMPPGS);
diff --git a/sys/kern/kern_kthread.c b/sys/kern/kern_kthread.c
index 134e9a22af70..7c0d6b5b0f9f 100644
--- a/sys/kern/kern_kthread.c
+++ b/sys/kern/kern_kthread.c
@@ -445,7 +445,7 @@ kproc_kthread_add(void (*func)(void *), void *arg,
 	char buf[100];
 	struct thread *td;
 
-	if (*procptr == 0) {
+	if (*procptr == NULL) {
 		error = kproc_create(func, arg,
 		    	procptr, flags, pages, "%s", procname);
 		if (error)
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index e980176abff2..9a41165b8f80 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -1444,7 +1444,7 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
 			p = LIST_FIRST(&allproc);
 		else
 			p = LIST_FIRST(&zombproc);
-		for (; p != 0; p = LIST_NEXT(p, p_list)) {
+		for (; p != NULL; p = LIST_NEXT(p, p_list)) {
 			/*
 			 * Skip embryonic processes.
 			 */
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index f57cd5889023..aae705e7b054 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -912,7 +912,7 @@ sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
 			name++;
 			continue;
 		}
-		lsp2 = 0;
+		lsp2 = NULL;
 		SLIST_FOREACH(oid, lsp, oid_link) {
 			if (oid->oid_number != *name)
 				continue;
@@ -1083,7 +1083,7 @@ sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
 {
 	char *p;
 	int error, oid[CTL_MAXNAME], len = 0;
-	struct sysctl_oid *op = 0;
+	struct sysctl_oid *op = NULL;
 	struct rm_priotracker tracker;
 
 	if (!req->newlen) 
diff --git a/sys/kern/link_elf.c b/sys/kern/link_elf.c
index 1579c28dd3b1..349a95ef06c9 100644
--- a/sys/kern/link_elf.c
+++ b/sys/kern/link_elf.c
@@ -1382,7 +1382,7 @@ link_elf_search_symbol(linker_file_t lf, caddr_t value,
 	u_long diff = off;
 	u_long st_value;
 	const Elf_Sym* es;
-	const Elf_Sym* best = 0;
+	const Elf_Sym* best = NULL;
 	int i;
 
 	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
@@ -1400,7 +1400,7 @@ link_elf_search_symbol(linker_file_t lf, caddr_t value,
 			}
 		}
 	}
-	if (best == 0)
+	if (best == NULL)
 		*diffp = off;
 	else
 		*diffp = diff;
diff --git a/sys/kern/link_elf_obj.c b/sys/kern/link_elf_obj.c
index 575a70607663..544bd253a6fc 100644
--- a/sys/kern/link_elf_obj.c
+++ b/sys/kern/link_elf_obj.c
@@ -1180,7 +1180,7 @@ link_elf_search_symbol(linker_file_t lf, caddr_t value,
 	u_long diff = off;
 	u_long st_value;
 	const Elf_Sym *es;
-	const Elf_Sym *best = 0;
+	const Elf_Sym *best = NULL;
 	int i;
 
 	for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) {
@@ -1198,7 +1198,7 @@ link_elf_search_symbol(linker_file_t lf, caddr_t value,
 			}
 		}
 	}
-	if (best == 0)
+	if (best == NULL)
 		*diffp = off;
 	else
 		*diffp = diff;
diff --git a/sys/kern/sysv_sem.c b/sys/kern/sysv_sem.c
index 22616b988d88..0063916c5194 100644
--- a/sys/kern/sysv_sem.c
+++ b/sys/kern/sysv_sem.c
@@ -980,8 +980,8 @@ sys_semop(struct thread *td, struct semop_args *uap)
 	size_t nsops = uap->nsops;
 	struct sembuf *sops;
 	struct semid_kernel *semakptr;
-	struct sembuf *sopptr = 0;
-	struct sem *semptr = 0;
+	struct sembuf *sopptr = NULL;
+	struct sem *semptr = NULL;
 	struct sem_undo *suptr;
 	struct mtx *sema_mtxp;
 	size_t i, j, k;
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index 62dfda663cbd..84354f3454b7 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -459,7 +459,7 @@ m_copym(struct mbuf *m, int off0, int len, int wait)
 		m = m->m_next;
 	}
 	np = &top;
-	top = 0;
+	top = NULL;
 	while (len > 0) {
 		if (m == NULL) {
 			KASSERT(len == M_COPYALL,
diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
index 0cdd43ba7706..cf9f4b1f75fc 100644
--- a/sys/kern/uipc_sockbuf.c
+++ b/sys/kern/uipc_sockbuf.c
@@ -593,7 +593,7 @@ sbappend_locked(struct sockbuf *sb, struct mbuf *m, int flags)
 
 	SOCKBUF_LOCK_ASSERT(sb);
 
-	if (m == 0)
+	if (m == NULL)
 		return;
 	sbm_clrprotoflags(m, flags);
 	SBLASTRECORDCHK(sb);
@@ -746,7 +746,7 @@ sbappendrecord_locked(struct sockbuf *sb, struct mbuf *m0)
 
 	SOCKBUF_LOCK_ASSERT(sb);
 
-	if (m0 == 0)
+	if (m0 == NULL)
 		return;
 	m_clrprotoflags(m0);
 	/*
@@ -885,7 +885,7 @@ sbappendcontrol_locked(struct sockbuf *sb, struct mbuf *m0,
 
 	SOCKBUF_LOCK_ASSERT(sb);
 
-	if (control == 0)
+	if (control == NULL)
 		panic("sbappendcontrol_locked");
 	space = m_length(control, &n) + m_length(m0, NULL);
 
diff --git a/sys/kern/uipc_syscalls.c b/sys/kern/uipc_syscalls.c
index 79444e0e725e..05703ef65c15 100644
--- a/sys/kern/uipc_syscalls.c
+++ b/sys/kern/uipc_syscalls.c
@@ -430,7 +430,7 @@ kern_accept4(struct thread *td, int s, struct sockaddr **name,
 	(void) fo_ioctl(nfp, FIONBIO, &tmp, td->td_ucred, td);
 	tmp = fflag & FASYNC;
 	(void) fo_ioctl(nfp, FIOASYNC, &tmp, td->td_ucred, td);
-	sa = 0;
+	sa = NULL;
 	error = soaccept(so, &sa);
 	if (error != 0)
 		goto noconnection;
diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index 40dc0c0c3203..ea902d7427f9 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -368,7 +368,7 @@ cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 		return tbp;
 
 	bp = trypbuf(&cluster_pbuf_freecnt);
-	if (bp == 0)
+	if (bp == NULL)
 		return tbp;
 
 	/*
diff --git a/sys/kern/vfs_export.c b/sys/kern/vfs_export.c
index 9eb523c212f5..e7a709d0e1e6 100644
--- a/sys/kern/vfs_export.c
+++ b/sys/kern/vfs_export.c
@@ -102,7 +102,7 @@ vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
 	register struct radix_node_head *rnh;
 	register int i;
 	struct radix_node *rn;
-	struct sockaddr *saddr, *smask = 0;
+	struct sockaddr *saddr, *smask = NULL;
 #if defined(INET6) || defined(INET)
 	int off;
 #endif
diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index f4b0596eb233..a1116e0a522f 100644
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -486,7 +486,7 @@ int
 lookup(struct nameidata *ndp)
 {
 	char *cp;		/* pointer into pathname argument */
-	struct vnode *dp = 0;	/* the directory we are searching */
+	struct vnode *dp = NULL;	/* the directory we are searching */
 	struct vnode *tdp;		/* saved dp */
 	struct mount *mp;		/* mount table entry */
 	struct prison *pr;
@@ -949,7 +949,7 @@ lookup(struct nameidata *ndp)
 int
 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
 {
-	struct vnode *dp = 0;		/* the directory we are searching */
+	struct vnode *dp = NULL;		/* the directory we are searching */
 	int wantparent;			/* 1 => wantparent or lockparent flag */
 	int rdonly;			/* lookup read-only flag bit */
 	int error = 0;
diff --git a/sys/libkern/strtol.c b/sys/libkern/strtol.c
index 4d64025dec2f..ea7dd5567285 100644
--- a/sys/libkern/strtol.c
+++ b/sys/libkern/strtol.c
@@ -123,7 +123,7 @@ strtol(nptr, endptr, base)
 		acc = neg ? LONG_MIN : LONG_MAX;
 	} else if (neg)
 		acc = -acc;
-	if (endptr != 0)
+	if (endptr != NULL)
 		*endptr = __DECONST(char *, any ? s - 1 : nptr);
 	return (acc);
 }
diff --git a/sys/libkern/strtoq.c b/sys/libkern/strtoq.c
index d85505689090..e83adb1f0e35 100644
--- a/sys/libkern/strtoq.c
+++ b/sys/libkern/strtoq.c
@@ -124,7 +124,7 @@ strtoq(const char *nptr, char **endptr, int base)
 		acc = neg ? QUAD_MIN : QUAD_MAX;
 	} else if (neg)
 		acc = -acc;
-	if (endptr != 0)
+	if (endptr != NULL)
 		*endptr = __DECONST(char *, any ? s - 1 : nptr);
 	return (acc);
 }
diff --git a/sys/libkern/strtoul.c b/sys/libkern/strtoul.c
index f7399dc13ef6..44adf5a30118 100644
--- a/sys/libkern/strtoul.c
+++ b/sys/libkern/strtoul.c
@@ -102,7 +102,7 @@ strtoul(nptr, endptr, base)
 		acc = ULONG_MAX;
 	} else if (neg)
 		acc = -acc;
-	if (endptr != 0)
+	if (endptr != NULL)
 		*endptr = __DECONST(char *, any ? s - 1 : nptr);
 	return (acc);
 }
diff --git a/sys/libkern/strtouq.c b/sys/libkern/strtouq.c
index f8303a0d2be8..49c3750b2a8a 100644
--- a/sys/libkern/strtouq.c
+++ b/sys/libkern/strtouq.c
@@ -101,7 +101,7 @@ strtouq(const char *nptr, char **endptr, int base)
 		acc = UQUAD_MAX;
 	} else if (neg)
 		acc = -acc;
-	if (endptr != 0)
+	if (endptr != NULL)
 		*endptr = __DECONST(char *, any ? s - 1 : nptr);
 	return (acc);
 }