--- shadow-4.0.18.2/libmisc/xmalloc.c	2007-10-07 12:47:22.000000000 +0100
+++ shadow-4.0.18.2/libmisc/xmalloc.c.new	2007-11-27 22:43:05.000000000 +0000
@@ -27,5 +27,6 @@
 
 char *xstrdup (const char *str)
 {
+	if(str == NULL) return NULL;
 	return strcpy (xmalloc (strlen (str) + 1), str);
 }