diff -r 3c8ba4a4092d config.def.h
--- a/config.def.h	Wed Apr 02 15:55:43 2008 +0200
+++ b/config.def.h	Wed Apr 02 15:59:51 2008 +0200
@@ -20,7 +20,7 @@
 
 /* geometries, s{x,y,w,h} and bh are already initualized here */
 /*   func name  bx  by  bw  wx  wy  ww     wh  mx  my       mw  mh     tx  ty     tw  th  mox moy mow moh */
-double mfact = 0.55;
+#define MFACT			0.55	/* master width factor [0.1 .. 0.9] */
 DEFGEOM(single,  0,  0, sw,  0, bh, sw, sh-bh, wx, wy, mfact*sw, wh, mx+mw, wy, ww-mw, wh,  wx, wy, ww, wh)
 DEFGEOM(dual,    0,  0,1280, 0, bh, ww, wh-bh, wx, wy, 1280,800-bh,  1280,  0, ww-mw, sh,  mx, my, mw, mh)
 
diff -r 3c8ba4a4092d dwm.c
--- a/dwm.c	Wed Apr 02 15:55:43 2008 +0200
+++ b/dwm.c	Wed Apr 02 15:59:51 2008 +0200
@@ -212,6 +212,7 @@
 int screen, sx, sy, sw, sh;
 int (*xerrorxlib)(Display *, XErrorEvent *);
 int bx, by, bw, bh, blw, bgw, mx, my, mw, mh, mox, moy, mow, moh, tx, ty, tw, th, wx, wy, ww, wh;
+double mfact;
 unsigned int numlockmask = 0;
 void (*handler[LASTEvent]) (XEvent *) = {
 	[ButtonPress] = buttonpress,
@@ -1469,14 +1470,18 @@
 setmfact(const char *arg) {
 	double d;
 
-	if(!arg || lt->isfloating)
+	if(lt->isfloating)
 		return;
-	d = strtod(arg, NULL);
-	if(arg[0] == '-' || arg[0] == '+')
-		d += mfact;
-	if(d < 0.1 || d > 0.9)
-		return;
-	mfact = d;
+	if(!arg)
+		mfact = MFACT;
+	else {
+		d = strtod(arg, NULL);
+		if(arg[0] == '-' || arg[0] == '+')
+			d += mfact;
+		if(d < 0.1 || d > 0.9)
+			return;
+		mfact = d;
+	}
 	setgeom(geom->symbol);
 }
 
@@ -1496,6 +1501,7 @@
 	sw = DisplayWidth(dpy, screen);
 	sh = DisplayHeight(dpy, screen);
 	bh = dc.font.height + 2;
+	mfact = MFACT;
 	geom = &geoms[0];
 	geom->apply();