diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index 8e471687236..5ba2aa893c9 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -35,7 +35,7 @@
  *
  *	@(#)null_subr.c	8.7 (Berkeley) 5/14/95
  *
- * $Id$
+ * $Id: null_subr.c,v 1.9 1997/02/22 09:40:21 peter Exp $
  */
 
 #include <sys/param.h>
@@ -122,7 +122,7 @@ loop:
 		}
 	}
 
-	return NULL;
+	return NULLVP;
 }
 
 
@@ -263,7 +263,7 @@ null_checkvp(vp, fil, lno)
 		panic("null_checkvp");
 	};
 #endif
-	if (a->null_lowervp == NULL) {
+	if (a->null_lowervp == NULLVP) {
 		/* Should never happen */
 		int i; u_long *p;
 		printf("vp = %x, ZERO ptr\n", vp);
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index 2d52f1ffc7c..a62b5e8ae97 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -36,7 +36,7 @@
  *	@(#)null_vfsops.c	8.2 (Berkeley) 1/21/94
  *
  * @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
- * $Id$
+ * $Id: null_vfsops.c,v 1.14 1997/02/22 09:40:21 peter Exp $
  */
 
 /*
@@ -127,7 +127,7 @@ nullfs_mount(mp, path, data, ndp, p)
 	lowerrootvp = ndp->ni_vp;
 
 	vrele(ndp->ni_dvp);
-	ndp->ni_dvp = NULL;
+	ndp->ni_dvp = NULLVP;
 
 	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
 				M_UFSMNT, M_WAITOK);	/* XXX */
diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
index 5ff5af24098..f145aa3e797 100644
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -37,11 +37,11 @@
  *
  * Ancestors:
  *	@(#)lofs_vnops.c	1.2 (Berkeley) 6/18/92
- *	$Id: null_vnops.c,v 1.15 1997/02/12 18:06:08 mpp Exp $
+ *	$Id: null_vnops.c,v 1.16 1997/02/22 09:40:22 peter Exp $
  *	...and...
  *	@(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
  *
- * $Id$
+ * $Id: null_vnops.c,v 1.16 1997/02/22 09:40:22 peter Exp $
  */
 
 /*
@@ -273,9 +273,9 @@ null_bypass(ap)
 		 * are of our type.  Check for and don't map any
 		 * that aren't.  (We must always map first vp or vclean fails.)
 		 */
-		if (i && (*this_vp_p == NULL ||
+		if (i && (*this_vp_p == NULLVP ||
 		    (*this_vp_p)->v_op != null_vnodeop_p)) {
-			old_vps[i] = NULL;
+			old_vps[i] = NULLVP;
 		} else {
 			old_vps[i] = *this_vp_p;
 			*(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p);
@@ -384,7 +384,7 @@ null_lookup(ap)
 		unlockargs.a_p = p;
 		vop_nounlock(&unlockargs);
 	}
-	if (vp != NULL && VOP_ISLOCKED(vp)) {
+	if (vp != NULLVP && VOP_ISLOCKED(vp)) {
 		lockargs.a_vp = vp;
 		lockargs.a_flags = LK_SHARED;
 		lockargs.a_p = p;
@@ -568,7 +568,7 @@ null_reclaim(ap)
 	 * so we can't call VOPs on ourself.
 	 */
 	/* After this assignment, this node will not be re-used. */
-	xp->null_lowervp = NULL;
+	xp->null_lowervp = NULLVP;
 	LIST_REMOVE(xp, null_hash);
 	FREE(vp->v_data, M_TEMP);
 	vp->v_data = NULL;
diff --git a/sys/miscfs/nullfs/null_subr.c b/sys/miscfs/nullfs/null_subr.c
index 8e471687236..5ba2aa893c9 100644
--- a/sys/miscfs/nullfs/null_subr.c
+++ b/sys/miscfs/nullfs/null_subr.c
@@ -35,7 +35,7 @@
  *
  *	@(#)null_subr.c	8.7 (Berkeley) 5/14/95
  *
- * $Id$
+ * $Id: null_subr.c,v 1.9 1997/02/22 09:40:21 peter Exp $
  */
 
 #include <sys/param.h>
@@ -122,7 +122,7 @@ loop:
 		}
 	}
 
-	return NULL;
+	return NULLVP;
 }
 
 
@@ -263,7 +263,7 @@ null_checkvp(vp, fil, lno)
 		panic("null_checkvp");
 	};
 #endif
-	if (a->null_lowervp == NULL) {
+	if (a->null_lowervp == NULLVP) {
 		/* Should never happen */
 		int i; u_long *p;
 		printf("vp = %x, ZERO ptr\n", vp);
diff --git a/sys/miscfs/nullfs/null_vfsops.c b/sys/miscfs/nullfs/null_vfsops.c
index 2d52f1ffc7c..a62b5e8ae97 100644
--- a/sys/miscfs/nullfs/null_vfsops.c
+++ b/sys/miscfs/nullfs/null_vfsops.c
@@ -36,7 +36,7 @@
  *	@(#)null_vfsops.c	8.2 (Berkeley) 1/21/94
  *
  * @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
- * $Id$
+ * $Id: null_vfsops.c,v 1.14 1997/02/22 09:40:21 peter Exp $
  */
 
 /*
@@ -127,7 +127,7 @@ nullfs_mount(mp, path, data, ndp, p)
 	lowerrootvp = ndp->ni_vp;
 
 	vrele(ndp->ni_dvp);
-	ndp->ni_dvp = NULL;
+	ndp->ni_dvp = NULLVP;
 
 	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
 				M_UFSMNT, M_WAITOK);	/* XXX */
diff --git a/sys/miscfs/nullfs/null_vnops.c b/sys/miscfs/nullfs/null_vnops.c
index 5ff5af24098..f145aa3e797 100644
--- a/sys/miscfs/nullfs/null_vnops.c
+++ b/sys/miscfs/nullfs/null_vnops.c
@@ -37,11 +37,11 @@
  *
  * Ancestors:
  *	@(#)lofs_vnops.c	1.2 (Berkeley) 6/18/92
- *	$Id: null_vnops.c,v 1.15 1997/02/12 18:06:08 mpp Exp $
+ *	$Id: null_vnops.c,v 1.16 1997/02/22 09:40:22 peter Exp $
  *	...and...
  *	@(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
  *
- * $Id$
+ * $Id: null_vnops.c,v 1.16 1997/02/22 09:40:22 peter Exp $
  */
 
 /*
@@ -273,9 +273,9 @@ null_bypass(ap)
 		 * are of our type.  Check for and don't map any
 		 * that aren't.  (We must always map first vp or vclean fails.)
 		 */
-		if (i && (*this_vp_p == NULL ||
+		if (i && (*this_vp_p == NULLVP ||
 		    (*this_vp_p)->v_op != null_vnodeop_p)) {
-			old_vps[i] = NULL;
+			old_vps[i] = NULLVP;
 		} else {
 			old_vps[i] = *this_vp_p;
 			*(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p);
@@ -384,7 +384,7 @@ null_lookup(ap)
 		unlockargs.a_p = p;
 		vop_nounlock(&unlockargs);
 	}
-	if (vp != NULL && VOP_ISLOCKED(vp)) {
+	if (vp != NULLVP && VOP_ISLOCKED(vp)) {
 		lockargs.a_vp = vp;
 		lockargs.a_flags = LK_SHARED;
 		lockargs.a_p = p;
@@ -568,7 +568,7 @@ null_reclaim(ap)
 	 * so we can't call VOPs on ourself.
 	 */
 	/* After this assignment, this node will not be re-used. */
-	xp->null_lowervp = NULL;
+	xp->null_lowervp = NULLVP;
 	LIST_REMOVE(xp, null_hash);
 	FREE(vp->v_data, M_TEMP);
 	vp->v_data = NULL;