diff --git a/area.c b/area.c
index deb9b10f..12dbc2f5 100644
--- a/area.c
+++ b/area.c
@@ -9,7 +9,7 @@
 
 Client *        
 sel_client_of_area(Area *a) {               
-	return a && a->sel ? a->sel->client : NULL;
+	return a && a->sel ? a->sel->client : nil;
 }
 
 Area *
@@ -32,7 +32,7 @@ create_area(View *v, Area *pos, unsigned int w) {
 	if(w < min_width)
 		w = min_width;
 	if(col_num && col_num * min_width + w > screen->rect.width)
-		return NULL;
+		return nil;
 	if(area_num > 1)
 		scale_view(v, screen->rect.width - w);
 	a = ixp_emallocz(sizeof(Area));
@@ -42,8 +42,8 @@ create_area(View *v, Area *pos, unsigned int w) {
 	a->rect.height = screen->rect.height - screen->brect.height;
 	a->mode = def.colmode;
 	a->rect.width = w;
-	a->frame = NULL;
-	a->sel = NULL;
+	a->frame = nil;
+	a->sel = nil;
 	a->next = *p;
 	*p = a;
 	v->sel = a;
@@ -64,10 +64,10 @@ destroy_area(Area *a) {
 	unsigned int i;
 	assert(!a->frame && "wmiiwm: fatal, destroying non-empty area");
 	if(v->revert == a)
-		v->revert = NULL;
+		v->revert = nil;
 	for(c=client; c; c=c->next)
 		if(c->revert == a)
-			c->revert = NULL;
+			c->revert = nil;
 	for(ta=v->area, i = 0; ta && ta->next != a; ta=ta->next, i++);
 	if(ta) {
 		ta->next = a->next;
@@ -83,7 +83,7 @@ destroy_area(Area *a) {
 static void
 place_client(Area *a, Client *c) {
 	static unsigned int mx, my;
-	static Bool *field = NULL;
+	static Bool *field = nil;
 	Frame *fr;
 	Bool fit = False;
 	BlitzAlign align = CENTER;
@@ -218,7 +218,7 @@ attach_to_area(Area *a, Frame *f, Bool send) {
 
 void
 detach_from_area(Area *a, Frame *f) {
-	Frame **ft, *pr = NULL;
+	Frame **ft, *pr = nil;
 	Client *c = f->client;
 	View *v = a->view;
 	Area *ta;
@@ -305,7 +305,7 @@ select_area(Area *a, char *arg) {
 		if(v == screen->sel)
 			focus_view(screen, v);
 		flush_masked_events(EnterWindowMask);
-		return NULL;
+		return nil;
 	}
 	else if(!strncmp(arg, "down", 5)) {
 		if(!f)
@@ -316,7 +316,7 @@ select_area(Area *a, char *arg) {
 		if(v == screen->sel)
 			focus_view(screen, v);
 		flush_masked_events(EnterWindowMask);
-		return NULL;
+		return nil;
 	}
 	else {
 		if(sscanf(arg, "%d", &i) != 1)
@@ -333,5 +333,5 @@ select_area(Area *a, char *arg) {
 	}
 	if(a->floating != new->floating)
 		v->revert = a;
-	return NULL;
+	return nil;
 }
diff --git a/bar.c b/bar.c
index 069e48c5..e48d823e 100644
--- a/bar.c
+++ b/bar.c
@@ -6,7 +6,7 @@
 #include <string.h>
 #include <stdlib.h>
 
-Bar *free_bars = NULL;
+Bar *free_bars = nil;
 
 Bar *
 create_bar(Bar **b_link, char *name) {
@@ -68,7 +68,7 @@ draw_bar(WMScreen *s) {
 	draw_tile(&s->bbrush);
 	if(!s->lbar && !s->rbar)
 		goto MapBar;
-	largest = b = tb = NULL;
+	largest = b = tb = nil;
 	tw = width = nb = size = 0;
 	for(b=s->lbar, nb=2 ;nb; --nb && (b = s->rbar))
 		for(; b; b=b->next) {
@@ -100,7 +100,7 @@ draw_bar(WMScreen *s) {
 		for(b=largest; b != tb->smaller; b=b->smaller)
 			b->brush.rect.width = floor(b->brush.rect.width * shrink);
 		width += tw * shrink;
-		tb=NULL;
+		tb=nil;
 	}
 	for(b=s->lbar, nb=2 ;nb; b=s->rbar, nb--)
 		for(; b; tb = b, b=b->next) {
diff --git a/client.c b/client.c
index 42c8526e..d24625b9 100644
--- a/client.c
+++ b/client.c
@@ -14,7 +14,7 @@ static char *Ebadcmd = "bad command",
 
 Client *
 sel_client() {
-	return screen->sel && screen->sel->sel->sel ? screen->sel->sel->sel->client : NULL;
+	return screen->sel && screen->sel->sel->sel ? screen->sel->sel->sel->client : nil;
 }
 
 Client *
@@ -28,7 +28,7 @@ Frame *
 frame_of_win(Window w) {
 	Client *c;
 	for(c=client; c && c->framewin != w; c=c->next);
-	return c ? c->frame : NULL;
+	return c ? c->frame : nil;
 }
 
 static void
@@ -36,7 +36,7 @@ update_client_name(Client *c) {
 	XTextProperty name;
 	XClassHint ch;
 	int n;
-	char **list = NULL;
+	char **list = nil;
 
 	name.nitems = 0;
 	c->name[0] = 0;
@@ -107,7 +107,7 @@ create_client(Window w, XWindowAttributes *wa) {
 	c->gc = XCreateGC(blz.dpy, c->framewin, 0, 0);
 	XSync(blz.dpy, False);
 	for(t=&client; *t; t=&(*t)->next);
-	c->next = *t; /* *t == NULL */
+	c->next = *t; /* *t == nil */
 	*t = c;
 	write_event("CreateClient 0x%x\n", c->win);
 	return c;
@@ -372,7 +372,7 @@ dummy_error_handler(Display *dpy, XErrorEvent *error) {
 
 void
 destroy_client(Client *c) {
-	char *dummy = NULL;
+	char *dummy = nil;
 	Client **tc;
 
 	XGrabServer(blz.dpy);
@@ -543,7 +543,7 @@ move_client(Client *c, char *arg) {
 	new.x += x;
 	new.y += y;
 	if(!f->area->floating)
-		resize_column(f->client, &new, NULL);
+		resize_column(f->client, &new, nil);
 	else
 		resize_client(f->client, &new, False);
 }
@@ -559,7 +559,7 @@ size_client(Client *c, char *arg) {
 	new.width += w;
 	new.height += h;
 	if(!f->area->floating)
-		resize_column(f->client, &new, NULL);
+		resize_column(f->client, &new, nil);
 	else
 		resize_client(f->client, &new, False);
 }
@@ -634,7 +634,7 @@ send_client(Frame *f, char *arg) {
 		focus_client(f->client, False);
 		focus_view(screen, f->view);
 	}
-	return NULL;
+	return nil;
 }
 
 /* convenience function */
@@ -701,7 +701,7 @@ apply_tags(Client *c, const char *tags) {
 		if(!strncmp(toks[i], "~", 2))
 			c->floating = True;
 		else if(!strncmp(toks[i], "!", 2))
-			toks[j++] = view ? screen->sel->name : "NULL";
+			toks[j++] = view ? screen->sel->name : "nil";
 		else if(strncmp(toks[i], "sel", 4)
 				&& strncmp(toks[i], ".", 2)
 				&& strncmp(toks[i], "..", 3))
@@ -720,7 +720,7 @@ apply_tags(Client *c, const char *tags) {
 			len -= strlen(c->tags);
 			toks[n++] = toks[i];
 		}
-	toks[n] = NULL;
+	toks[n] = nil;
 	update_client_views(c, toks);
 	XChangeProperty(blz.dpy, c->win, tags_atom, XA_STRING, 8,
 			PropModeReplace, (unsigned char *)c->tags, strlen(c->tags));
@@ -733,7 +733,7 @@ match_tags(Client *c, const char *prop) {
 
 	for(r=def.tagrules.rule; r; r=r->next)
 		if(!regexec(&r->regex, prop, 1, &tmpregm, 0))
-			if(!strlen(c->tags) || !strncmp(c->tags, "NULL", 4))
+			if(!strlen(c->tags) || !strncmp(c->tags, "nil", 4))
 				apply_tags(c, r->value);
 }
 
@@ -742,14 +742,14 @@ apply_rules(Client *c) {
 	if(def.tagrules.string)
 		match_tags(c, c->props);
 	if(!strlen(c->tags))
-		apply_tags(c, "NULL");
+		apply_tags(c, "nil");
 }
 
 char *
 message_client(Client *c, char *message) {
 	if(!strncmp(message, "kill", 5)) {
 		kill_client(c);
-		return NULL;
+		return nil;
 	}
 	return Ebadcmd;
 }
diff --git a/column.c b/column.c
index e1579b7c..9d8d0fa2 100644
--- a/column.c
+++ b/column.c
@@ -27,7 +27,7 @@ str_of_column_mode(int mode) {
 	case Colmax: return "max"; break;
 	default: break;
 	}
-	return NULL;
+	return nil;
 }
 
 int
@@ -216,9 +216,9 @@ match_horiz(Area *a, XRectangle *r) {
 
 static void
 drop_resize(Frame *f, XRectangle *new) {
-	Area *west = NULL, *east = NULL, *a = f->area;
+	Area *west = nil, *east = nil, *a = f->area;
 	View *v = a->view;
-	Frame *north = NULL, *south = NULL;
+	Frame *north = nil, *south = nil;
 	unsigned int min_height = 2 * labelh(&def.font);
 	unsigned int min_width = screen->rect.width/NCOL;
 
@@ -317,10 +317,10 @@ static Frame *
 frame_of_point(XPoint *pt) {
 	Area *a;
 	View *v = screen->sel;
-	Frame *f = NULL;
+	Frame *f = nil;
 
 	if(!v)
-		return NULL;
+		return nil;
 	for(a=v->area->next; a && !ispointinrect(pt->x, pt->y, &a->rect);
 		a=a->next);
 	if(a)
@@ -340,7 +340,7 @@ drop_move(Frame *f, XRectangle *nrect) {
 
 	v = f->view;
 	high = 0;
-	a_high = NULL;
+	a_high = nil;
 
 	for(a = v->area->next; a; a = a->next) {
 		arect = &a->rect;
@@ -414,7 +414,7 @@ drop_move_old(Frame *f, XRectangle *new, XPoint *pt) {
 	Frame *ft;
 	View *v;
 
-	tgt = NULL;
+	tgt = nil;
 	src = f->area;
 	v = src->view;
 	if(!pt)
@@ -479,7 +479,7 @@ Area *
 new_column(View *v, Area *pos, unsigned int w) {
 	Area *a = create_area(v, pos, w);
 	if(!a)
-		return NULL;
+		return nil;
 	arrange_view(v);
 	return a;
 }
diff --git a/draw.c b/draw.c
index 54451676..d57b7843 100644
--- a/draw.c
+++ b/draw.c
@@ -10,7 +10,7 @@ unsigned int
 textwidth_l(BlitzFont *font, char *text, unsigned int len) {
 	if(font->set) {
 		XRectangle r;
-		XmbTextExtents(font->set, text, len, NULL, &r);
+		XmbTextExtents(font->set, text, len, nil, &r);
 		return r.width;
 	}
 	return XTextWidth(font->xfont, text, len);
@@ -24,7 +24,7 @@ textwidth(BlitzFont *font, char *text) {
 void
 loadfont(Blitz *blitz, BlitzFont *font) {
 	char *fontname = font->fontstr;
-	char **missing = NULL, *def = "?";
+	char **missing = nil, *def = "?";
 	int n;
 
 	if(font->set)
@@ -54,7 +54,7 @@ loadfont(Blitz *blitz, BlitzFont *font) {
 	else {
 		if(font->xfont)
 			XFreeFont(blitz->dpy, font->xfont);
-		font->xfont = NULL;
+		font->xfont = nil;
 		font->xfont = XLoadQueryFont(blitz->dpy, fontname);
 		if (!font->xfont) {
 			fprintf(stderr, "%s", "wmii: error, cannot load 'fixed' font\n");
@@ -224,5 +224,5 @@ parse_colors(char **buf, int *buflen, BlitzColor *col) {
 		(*buf)++;
 		(*buflen)--;
 	}
-	return NULL;
+	return nil;
 }
diff --git a/fs.c b/fs.c
index 09b5723a..d7c14bfc 100644
--- a/fs.c
+++ b/fs.c
@@ -70,8 +70,8 @@ static char
 
 /* Global Vars */
 /***************/
-FileId *free_fileid = NULL;
-P9Req *pending_event_reads = NULL;
+FileId *free_fileid = nil;
+P9Req *pending_event_reads = nil;
 FidLink *pending_event_fids;
 P9Srv p9srv = {
 	.open=	fs_open,
@@ -100,25 +100,25 @@ dirtab_root[]=	 {{".",		P9QTDIR,	FsRoot,		0500|P9DMDIR },
 		  {"event",	P9QTFILE,	FsFEvent,	0600 },
 		  {"keys",	P9QTFILE,	FsFKeys,	0600 },
 		  {"tagrules",	P9QTFILE,	FsFTagRules,	0600 }, 
-		  {NULL}},
+		  {nil}},
 dirtab_clients[]={{".",		P9QTDIR,	FsDClients,	0500|P9DMDIR },
 		  {"",		P9QTDIR,	FsDClient,	0500|P9DMDIR },
-		  {NULL}},
+		  {nil}},
 dirtab_client[]= {{".",		P9QTDIR,	FsDClient,	0500|P9DMDIR },
 		  {"ctl",	P9QTAPPEND,	FsFCctl,	0600|P9DMAPPEND },
 		  {"tags",	P9QTFILE,	FsFCtags,	0600 },
 		  {"props",	P9QTFILE,	FsFprops,	0400 },
-		  {NULL}},
+		  {nil}},
 dirtab_bars[]=	 {{".",		P9QTDIR,	FsDBars,	0700|P9DMDIR },
 		  {"",		P9QTFILE,	FsFBar,		0600 },
-		  {NULL}},
+		  {nil}},
 dirtab_tags[]=	 {{".",		P9QTDIR,	FsDTags,	0500|P9DMDIR },
 		  {"",		P9QTDIR,	FsDTag,		0500|P9DMDIR },
-		  {NULL}},
+		  {nil}},
 dirtab_tag[]=	 {{".",		P9QTDIR,	FsDTag,		0500|P9DMDIR },
 		  {"ctl",	P9QTAPPEND,	FsFTctl,	0600|P9DMAPPEND },
 		  {"index",	P9QTFILE,	FsFTindex,	0400 },
-		  {NULL}};
+		  {nil}};
 /* Writing the lists separately and using an array of their references
  * removes the need for casting and allows for C90 conformance,
  * since otherwise we would need to use compound literals */
@@ -151,7 +151,7 @@ get_file() {
 	temp = free_fileid;
 	free_fileid = temp->next;
 	temp->nref = 1;
-	temp->next = NULL;
+	temp->next = nil;
 	return temp;
 }
 
@@ -279,7 +279,7 @@ message_root(char *message)
 	}
 	else
 		return Ebadcmd;
-	return NULL;
+	return nil;
 }
 
 char *
@@ -303,8 +303,8 @@ respond_event(P9Req *r) {
 	if(f->content.buf) {
 		r->ofcall.data.rread.data = (void *)f->content.buf;
 		r->ofcall.data.rread.count = strlen(f->content.buf);
-		respond(r, NULL);
-		f->content.buf = NULL;
+		respond(r, nil);
+		f->content.buf = nil;
 	}else{
 		r->aux = pending_event_reads;
 		pending_event_reads = r;
@@ -345,8 +345,8 @@ dostat(Stat *s, unsigned int len, FileId *f) {
 	s->qid.version = 0;
 	s->qid.type = f->tab.qtype;
 	s->mode = f->tab.perm;
-	s->atime = time(NULL);
-	s->mtime = time(NULL);
+	s->atime = time(nil);
+	s->mtime = time(nil);
 	s->length = len;
 	s->name = f->tab.name;
 	s->uid = user;
@@ -369,10 +369,10 @@ lookup_file(FileId *parent, char *name)
 	unsigned int id;
 
 	if(!(parent->tab.perm & P9DMDIR))
-		return NULL;
+		return nil;
 	dir = dirtab[parent->tab.type];
 	last = &ret;
-	ret = NULL;
+	ret = nil;
 	for(; dir->name; dir++) {
 		/* Dynamic dirs */
 		if(!*dir->name) { /* strlen(dir->name) == 0 */
@@ -479,7 +479,7 @@ lookup_file(FileId *parent, char *name)
 		continue;
 	}
 LastItem:
-	*last = NULL;
+	*last = nil;
 	return ret;
 }
 
@@ -490,12 +490,12 @@ fs_attach(P9Req *r) {
 	FileId *f = get_file();
 	f->tab = dirtab[FsRoot][0];
 	f->tab.name = ixp_estrdup("/");
-	f->content.ref = NULL; /* shut up valgrind */
+	f->content.ref = nil; /* shut up valgrind */
 	r->fid->aux = f;
 	r->fid->qid.type = f->tab.qtype;
 	r->fid->qid.path = QID(f->tab.type, 0);
 	r->ofcall.data.rattach.qid = r->fid->qid;
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 void
@@ -547,7 +547,7 @@ fs_walk(P9Req *r) {
 	}
 	r->newfid->aux = f;
 	r->ofcall.data.rwalk.nwqid = i;
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 unsigned int
@@ -578,7 +578,7 @@ fs_stat(P9Req *r) {
 	buf = ixp_emallocz(size);
 	r->ofcall.data.rstat.stat = buf;
 	ixp_pack_stat(&buf, &size, &s);
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 void
@@ -596,7 +596,7 @@ fs_read(P9Req *r) {
 		size = r->ifcall.data.tread.count;
 		buf = ixp_emallocz(size);
 		r->ofcall.data.rread.data = buf;
-		tf = f = lookup_file(f, NULL);
+		tf = f = lookup_file(f, nil);
 		/* Note: f->tab.name == "." so we skip it */
 		for(f=f->next; f; f=f->next) {
 			dostat(&s, fs_size(f), f);
@@ -613,57 +613,57 @@ fs_read(P9Req *r) {
 			free_file(f);
 		}
 		r->ofcall.data.rread.count = r->ifcall.data.tread.count - size;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	}
 	else{
 		switch(f->tab.type) {
 		case FsFprops:
 			write_buf(r, (void *)f->content.client->props, strlen(f->content.client->props));
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFColRules:
 		case FsFTagRules:
 			write_buf(r, (void *)f->content.rule->string, f->content.rule->size);
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFKeys:
 			write_buf(r, (void *)def.keys, def.keyssz);
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFCtags:
 			write_buf(r, (void *)f->content.client->tags, strlen(f->content.client->tags));
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFTctl:
 			write_buf(r, (void *)f->content.view->name, strlen(f->content.view->name));
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFBar:
 			write_buf(r, (void *)f->content.bar->buf, strlen(f->content.bar->buf));
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFRctl:
 			buf = read_root_ctl();
 			write_buf(r, buf, strlen(buf));
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFCctl:
 			if(r->ifcall.data.tread.offset) {
-				respond(r, NULL);
+				respond(r, nil);
 				return;
 			}
 			r->ofcall.data.rread.data = ixp_emallocz(16);
 			n = snprintf(r->ofcall.data.rread.data, 16, "0x%x", (unsigned int)f->index);
 			assert(n >= 0);
 			r->ofcall.data.rread.count = n;
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFTindex:
 			buf = (char *)view_index(f->content.view);
 			n = strlen(buf);
 			write_buf(r, (void *)buf, n);
-			respond(r, NULL);
+			respond(r, nil);
 			return;
 		case FsFEvent:
 			respond_event(r);
@@ -679,11 +679,11 @@ fs_read(P9Req *r) {
 void
 fs_write(P9Req *r) {
 	FileId *f;
-	char *errstr = NULL;
+	char *errstr = nil;
 	unsigned int i;
 
 	if(r->ifcall.data.twrite.count == 0) {
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	}
 	f = r->fid->aux;
@@ -691,25 +691,25 @@ fs_write(P9Req *r) {
 	case FsFColRules:
 	case FsFTagRules:
 		write_to_buf(r, &f->content.rule->string, &f->content.rule->size, 0);
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFKeys:
 		write_to_buf(r, &def.keys, &def.keyssz, 0);
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFCtags:
 		data_to_cstring(r);
 		i=strlen(f->content.client->tags);
 		write_to_buf(r, &f->content.client->tags, &i, 255);
 		r->ofcall.data.rwrite.count = i- r->ifcall.data.twrite.offset;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFBar:
 		/* XXX: This should validate after each write */
 		i = strlen(f->content.bar->buf);
 		write_to_buf(r, &f->content.bar->buf, &i, 279);
 		r->ofcall.data.rwrite.count = i - r->ifcall.data.twrite.offset;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFCctl:
 		data_to_cstring(r);
@@ -718,7 +718,7 @@ fs_write(P9Req *r) {
 			return;
 		}
 		r->ofcall.data.rwrite.count = r->ifcall.data.twrite.count;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFTctl:
 		data_to_cstring(r);
@@ -727,7 +727,7 @@ fs_write(P9Req *r) {
 			return;
 		}
 		r->ofcall.data.rwrite.count = r->ifcall.data.twrite.count;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFRctl:
 		data_to_cstring(r);
@@ -746,7 +746,7 @@ fs_write(P9Req *r) {
 			return;
 		}
 		r->ofcall.data.rwrite.count = r->ifcall.data.twrite.count;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	case FsFEvent:
 		if(r->ifcall.data.twrite.data[r->ifcall.data.twrite.count-1] == '\n')
@@ -754,7 +754,7 @@ fs_write(P9Req *r) {
 		else
 			write_event("%.*s\n", r->ifcall.data.twrite.count, r->ifcall.data.twrite.data);
 		r->ofcall.data.rwrite.count = r->ifcall.data.twrite.count;
-		respond(r, NULL);
+		respond(r, nil);
 		return;
 	}
 	/* This is an assert because it should this should not be called if
@@ -791,7 +791,7 @@ fs_open(P9Req *r) {
 		respond(r, Enoperm);
 		return;
 	}
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 void
@@ -818,7 +818,7 @@ fs_create(P9Req *r) {
 		r->ofcall.data.rcreate.qid.path = QID(f->tab.type, f->id);
 		f->next = r->fid->aux;
 		r->fid->aux = f;
-		respond(r, NULL);
+		respond(r, nil);
 		break;
 	}
 }
@@ -835,7 +835,7 @@ fs_remove(P9Req *r) {
 	case FsFBar:
 		destroy_bar(f->next->content.bar_p, f->content.bar);
 		draw_bar(screen);
-		respond(r, NULL);
+		respond(r, nil);
 		break;
 	}
 }
@@ -887,7 +887,7 @@ fs_clunk(P9Req *r) {
 			}
 		break;
 	}
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 void
@@ -900,7 +900,7 @@ fs_flush(P9Req *r) {
 			respond(r->oldreq, Einterrupted);
 			break;
 		}
-	respond(r, NULL);
+	respond(r, nil);
 }
 
 void
diff --git a/key.c b/key.c
index 2394c1cd..8499dcf9 100644
--- a/key.c
+++ b/key.c
@@ -156,7 +156,7 @@ emulate_key_press(unsigned long mod, KeyCode key) {
 
 static Key *
 match_keys(Key *k, unsigned long mod, KeyCode keycode, Bool seq) {
-	Key *ret = NULL, *next;
+	Key *ret = nil, *next;
 
 	for(next = k->tnext; k; (k=next) && (next=k->tnext)) {
 		if(seq)
diff --git a/main.c b/main.c
index 5183ee6a..14c22868 100644
--- a/main.c
+++ b/main.c
@@ -197,7 +197,7 @@ cleanup() {
 int
 main(int argc, char *argv[]) {
 	int i;
-	char *address = NULL, *wmiirc = NULL, *namespace, *errstr;
+	char *address = nil, *wmiirc = nil, *namespace, *errstr;
 	WMScreen *s;
 	struct passwd *passwd;
 	XSetWindowAttributes wa;
@@ -264,7 +264,7 @@ main(int argc, char *argv[]) {
 	}
 	XSetErrorHandler(0);
 	x_error_handler = XSetErrorHandler(wmii_error_handler);
-	errstr = NULL;
+	errstr = nil;
 	i = ixp_create_sock(address, &errstr);
 	if(i < 0)
 		ixp_eprint("wmiiwm: fatal: %s\n", errstr);
@@ -281,7 +281,7 @@ main(int argc, char *argv[]) {
 			close(i);
 			close(ConnectionNumber(blz.dpy));
 			snprintf(execstr, name_len, "exec %s", wmiirc);
-			execl("/bin/sh", "sh", "-c", execstr, NULL);
+			execl("/bin/sh", "sh", "-c", execstr, nil);
 			ixp_eprint("wmiiwm: can't exec \"%s\": %s\n", wmiirc, strerror(errno));
 		case -1:
 			perror("wmiiwm: cannot fork wmiirc");
@@ -291,19 +291,19 @@ main(int argc, char *argv[]) {
 	}
 
 	/* IXP server */
-	ixp_server_open_conn(&srv, i, &p9srv, serve_9pcon, NULL);
+	ixp_server_open_conn(&srv, i, &p9srv, serve_9pcon, nil);
 	/* X server */
-	ixp_server_open_conn(&srv, ConnectionNumber(blz.dpy), NULL, check_x_event, NULL);
-	view = NULL;
-	client = NULL;
-	key = NULL;
+	ixp_server_open_conn(&srv, ConnectionNumber(blz.dpy), nil, check_x_event, nil);
+	view = nil;
+	client = nil;
+	key = nil;
 	passwd = getpwuid(getuid());
 	user = ixp_estrdup(passwd->pw_name);
-	def.colrules.string = NULL;
+	def.colrules.string = nil;
 	def.colrules.size = 0;
-	def.tagrules.string = NULL;
+	def.tagrules.string = nil;
 	def.tagrules.size = 0;
-	def.keys = NULL;
+	def.keys = nil;
 	def.keyssz = 0;
 	def.font.fontstr = ixp_estrdup(BLITZ_FONT);
 	def.border = 2;
@@ -322,9 +322,9 @@ main(int argc, char *argv[]) {
 	screens = ixp_emallocz(num_screens * sizeof(*screens));
 	for(i = 0; i < num_screens; i++) {
 		s = &screens[i];
-		s->lbar = NULL;
-		s->rbar = NULL;
-		s->sel = NULL;
+		s->lbar = nil;
+		s->rbar = nil;
+		s->sel = nil;
 		init_screen(s);
 		pmap = XCreatePixmap(blz.dpy, blz.root, s->rect.width, s->rect.height,
 				DefaultDepth(blz.dpy, blz.screen));
diff --git a/mouse.c b/mouse.c
index 99b71749..b131f397 100644
--- a/mouse.c
+++ b/mouse.c
@@ -105,7 +105,7 @@ BlitzAlign
 snap_rect(XRectangle *rects, int num, XRectangle *current,
           BlitzAlign *mask, int snap)
 {
-	SnapArgs a = { rects, num, 0, 0, 0, 0, *mask, NULL };
+	SnapArgs a = { rects, num, 0, 0, 0, 0, *mask, nil };
 	int dx = snap + 1, dy = snap + 1;
 	BlitzAlign ret;
 
@@ -171,7 +171,7 @@ do_mouse_resize(Client *c, BlitzAlign align) {
 	Frame *f = c->sel;
 	Bool floating = f->area->floating;
 	int snap = floating ? screen->rect.height / 66 : 0;
-	XRectangle *rects = floating ? rects_of_view(f->area->view, &num) : NULL;
+	XRectangle *rects = floating ? rects_of_view(f->area->view, &num) : nil;
 	XRectangle frect = f->rect, ofrect;
 	XRectangle origin = frect;
 	XPoint pt;
@@ -215,7 +215,7 @@ do_mouse_resize(Client *c, BlitzAlign align) {
 			pt.x = pt_x;
 			pt.y = pt_y;
 			if(!floating)
-				resize_column(c, &frect, (align == CENTER) ? &pt : NULL);
+				resize_column(c, &frect, (align == CENTER) ? &pt : nil);
 			else
 				resize_client(c, &frect, False);
 
diff --git a/rule.c b/rule.c
index f76f04a3..87ce19c6 100644
--- a/rule.c
+++ b/rule.c
@@ -34,7 +34,7 @@ void
 update_rules(Rule **rule, const char *data) {
 	int mode = IGNORE;
 	Rule *rul;
-	char *p, *r = NULL, *v = NULL, regex[256], value[256];
+	char *p, *r = nil, *v = nil, regex[256], value[256];
 
 	if(!data || !strlen(data))
 		return;
diff --git a/view.c b/view.c
index 0b14ede9..1cbdd695 100644
--- a/view.c
+++ b/view.c
@@ -39,7 +39,7 @@ assign_sel_view(View *v) {
 
 Client *
 sel_client_of_view(View *v) {
-	return v->sel && v->sel->sel ? v->sel->sel->client : NULL;
+	return v->sel && v->sel->sel ? v->sel->sel->client : nil;
 }
 
 View *
@@ -62,7 +62,7 @@ create_view(const char *name) {
 
 	v->id = id++;
 	strncpy(v->name, name, sizeof(v->name));
-	create_area(v, NULL, 0);
+	create_area(v, nil, 0);
 	create_area(v, v->area, 0);
 	v->area->floating = True;
 	for(i=&view; *i; i=&(*i)->next)
@@ -150,7 +150,7 @@ attach_to_view(View *v, Frame *f) {
 	Client *c = f->client;
 	unsigned int i;
 
-	c->revert = NULL;
+	c->revert = nil;
 	a = v->sel;
 	if(c->trans || c->floating || c->fixedsize
 		|| (c->rect.width == screen->rect.width && c->rect.height == screen->rect.height))
@@ -171,7 +171,7 @@ restack_view(View *v) {
 	Frame *f;
 	Client *c;
 	unsigned int n, i;
-	static Window *wins = NULL;
+	static Window *wins = nil;
 	static unsigned int winssz = 0;
 
 	i = 0;
@@ -326,7 +326,7 @@ client_of_message(View *v, char *message, unsigned int *next) {
 	if(!id)
 		sscanf(message, "%lu %n", &id, next);
 	if(!id)
-		return NULL;
+		return nil;
     for(c=client; c && c->win!=id; c=c->next);
 	return c;
 }
@@ -343,7 +343,7 @@ area_of_message(View *v, char *message, unsigned int *next) {
 	if(!strncmp(message, "~ ", 2))
 		return v->area;
 	if(1 != sscanf(message, "%d %n", &i, next) || i == 0)
-		return NULL;
+		return nil;
 	for(a=v->area; i && a; a=a->next, i--);
 	return a;
 }
@@ -380,7 +380,7 @@ message_view(View *v, char *message) {
 		if(v == screen->sel)
 			focus_view(screen, v);
 		draw_frames();
-		return NULL;
+		return nil;
 	}
 	return Ebadvalue;
 }
@@ -392,8 +392,8 @@ update_views() {
 
 	for(v=view; v; v=v->next)
 		update_frame_selectors(v);
-	if(old && !strncmp(old->name, "NULL", 4))
-		old = NULL;
+	if(old && !strncmp(old->name, "nil", 4))
+		old = nil;
 	for((v=view) && (n=v->next); v; (v=n) && (n=v->next))
 		if((v != old) && is_empty(v))
 			destroy_view(v);
diff --git a/wmii.h b/wmii.h
index a28eb34a..1548816e 100644
--- a/wmii.h
+++ b/wmii.h
@@ -10,6 +10,8 @@
 
 #include <ixp.h>
 
+#define nil	((void*)0)
+
 #define BLITZ_FONT		"-*-fixed-medium-r-normal-*-13-*-*-*-*-*-*-*"
 #define BLITZ_FOCUSCOLORS		"#ffffff #335577 #447799"
 #define BLITZ_SELCOLORS		"#444444 #bbbbbb #556088"