Index: /trunk/src/VBox/Additions/linux/sharedfolders/vbsfmount.c
===================================================================
--- /trunk/src/VBox/Additions/linux/sharedfolders/vbsfmount.c	(revision 31204)
+++ /trunk/src/VBox/Additions/linux/sharedfolders/vbsfmount.c	(revision 31205)
@@ -19,4 +19,7 @@
 #include "vbsfmount.h"
 
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
 #include <ctype.h>
 #include <mntent.h>