--- a/dwm.c	Wed Jun 11 17:01:30 2008 +0100
+++ b/dwm.c	Wed Jun 11 19:42:24 2008 +0100
@@ -1478,7 +1478,7 @@
 
 void
 togglelayout(const Arg *arg) {
-	if(arg->v)
+	if(arg && arg->v)
 		lt = (Layout *)arg->v;
 	else if(++lt == &layouts[LENGTH(layouts)])
 		lt = &layouts[0];