--- include/dos_inc.h	2010-05-10 17:43:54.000000000 +0000
+++ include/dos_inc.h	2011-06-17 20:42:43.982548979 +0000
@@ -28,6 +28,8 @@
 #include "mem.h"
 #endif
 
+#include <stddef.h> // for offsetof
+
 #ifdef _MSC_VER
 #pragma pack (1)
 #endif