diff -up cups-1.5b1/scheduler/auth.c.peercred cups-1.5b1/scheduler/auth.c
--- cups-1.5b1/scheduler/auth.c.peercred	2011-05-20 05:49:49.000000000 +0200
+++ cups-1.5b1/scheduler/auth.c	2011-05-23 18:00:18.000000000 +0200
@@ -52,6 +52,7 @@
  * Include necessary headers...
  */
 
+#define _GNU_SOURCE
 #include "cupsd.h"
 #include <grp.h>
 #ifdef HAVE_SHADOW_H