Index: src/VBox/Devices/Network/slirp/slirp.c
===================================================================
--- src/VBox/Devices/Network/slirp/slirp.c	(revision 37995)
+++ src/VBox/Devices/Network/slirp/slirp.c	(working copy)
@@ -41,6 +41,8 @@
  * THE SOFTWARE.
  */
 
+#define _GNU_SOURCE 1
+
 #include "slirp.h"
 #ifdef RT_OS_OS2
 # include <paths.h>
