diff -rup dwm.orig/tile.h dwm/tile.h
--- dwm.orig/tile.h	2007-08-15 21:53:12.000000000 +0200
+++ dwm/tile.h	2007-08-17 11:55:27.000000000 +0200
@@ -1,6 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 
 /* tile.c */
-void addtomwfact(const char *arg);	/* adds arg value [0.1 .. 0.9] to master width factor */
+void setmwfact(const char *arg);	/* sets master width factor */
 void tile(void);			/* arranges all windows tiled */
 void zoom(const char *arg);		/* zooms the focused client to master area, arg is ignored */
diff -rup dwm.orig/tile.c dwm/tile.c
--- dwm.orig/tile.c	2007-08-16 09:21:04.000000000 +0200
+++ dwm/tile.c	2007-08-17 12:03:07.000000000 +0200
@@ -9,8 +9,9 @@ static double mwfact = MWFACT;
 /* extern */
 
 void
-addtomwfact(const char *arg) {
-	double delta;
+setmwfact(const char *arg) {
+	char sign;
+	double delta, newfact;
 
 	if(!isarrange(tile))
 		return;
@@ -18,9 +19,24 @@ addtomwfact(const char *arg) {
 	/* arg handling, manipulate mwfact */
 	if(arg == NULL)
 		mwfact = MWFACT;
-	else if(1 == sscanf(arg, "%lf", &delta)) {
-		if(delta + mwfact > 0.1 && delta + mwfact < 0.9)
-			mwfact += delta;
+	else {
+		switch(arg[0]) {
+			case '-':
+			case '+':
+				if(2 != sscanf(arg, "%c%lf", &sign, &delta))
+					return;
+				newfact = mwfact + (sign=='-' ? -1 : 1) * delta;
+				break;
+			default:
+				if(1 != sscanf(arg, "%lf", &newfact))
+					return;
+				break;
+		}
+		if(newfact < 0.1)
+			newfact = 0.1;
+		else if(newfact > 0.9)
+			newfact = 0.9;
+		mwfact = newfact;
 	}
 	arrange();
 }
diff -rup dwm.orig/config.arg.h dwm/config.arg.h
--- dwm.orig/config.arg.h	2007-08-17 10:39:09.000000000 +0200
+++ dwm/config.arg.h	2007-08-17 11:56:18.000000000 +0200
@@ -48,8 +48,8 @@ Key keys[] = { \
 	{ MODKEY,			XK_b,		togglebar,	NULL }, \
 	{ MODKEY,			XK_j,		focusnext,	NULL }, \
 	{ MODKEY,			XK_k,		focusprev,	NULL }, \
-	{ MODKEY,			XK_h,		addtomwfact,	"-0.05" }, \
-	{ MODKEY,			XK_l,		addtomwfact,	"0.05" }, \
+	{ MODKEY,			XK_h,		setmwfact,	"-0.05" }, \
+	{ MODKEY,			XK_l,		setmwfact,	"+0.05" }, \
 	{ MODKEY,			XK_m,		togglemax,	NULL }, \
 	{ MODKEY,			XK_Return,	zoom,		NULL }, \
 	{ MODKEY|ShiftMask,		XK_space,	togglefloating,	NULL }, \
diff -rup dwm.orig/config.default.h dwm/config.default.h
--- dwm.orig/config.default.h	2007-08-17 10:39:09.000000000 +0200
+++ dwm/config.default.h	2007-08-17 11:56:28.000000000 +0200
@@ -46,8 +46,8 @@ Key keys[] = { \
 	{ MODKEY,			XK_b,		togglebar,	NULL }, \
 	{ MODKEY,			XK_j,		focusnext,	NULL }, \
 	{ MODKEY,			XK_k,		focusprev,	NULL }, \
-	{ MODKEY,			XK_h,		addtomwfact,	"-0.05" }, \
-	{ MODKEY,			XK_l,		addtomwfact,	"0.05" }, \
+	{ MODKEY,			XK_h,		setmwfact,	"-0.05" }, \
+	{ MODKEY,			XK_l,		setmwfact,	"+0.05" }, \
 	{ MODKEY,			XK_m,		togglemax,	NULL }, \
 	{ MODKEY,			XK_Return,	zoom,		NULL }, \
 	{ MODKEY|ShiftMask,		XK_space,	togglefloating,	NULL }, \