diff --git a/tools/xenpaging/xenpaging.c b/tools/xenpaging/xenpaging.c
index d290725f30..38e78c2967 100644
--- a/tools/xenpaging/xenpaging.c
+++ b/tools/xenpaging/xenpaging.c
@@ -19,6 +19,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#define _XOPEN_SOURCE	600
 
 #include <inttypes.h>
 #include <stdlib.h>