--- /dev/null
+--- a/vmcore-dmesg/vmcore-dmesg.c
++++ b/vmcore-dmesg/vmcore-dmesg.c
+@@ -1,6 +1,8 @@
+ #define _XOPEN_SOURCE 600
+ #define _LARGEFILE_SOURCE 1
+ #define _FILE_OFFSET_BITS 64
++#define _GNU_SOURCE
++
+ #include <endian.h>
+ #include <byteswap.h>
+ #include <stdio.h>