diff -Naur shadow-4.0.6-orig/libmisc/xmalloc.c shadow-4.0.6/libmisc/xmalloc.c
--- shadow-4.0.6-orig/libmisc/xmalloc.c	2004-05-06 14:31:33.000000000 -0700
+++ shadow-4.0.6/libmisc/xmalloc.c	2005-01-13 11:49:38.000000000 -0800
@@ -28,5 +28,6 @@
 
 char *xstrdup (const char *str)
 {
+	if(str == NULL) return NULL;
 	return strcpy (xmalloc (strlen (str) + 1), str);
 }