diff --git a/src/dos/dos_classes.cpp b/src/dos/dos_classes.cpp
index 17411c3f..6bd5819b 100644
--- a/src/dos/dos_classes.cpp
+++ b/src/dos/dos_classes.cpp
@@ -16,7 +16,7 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* $Id: dos_classes.cpp,v 1.45 2005-08-08 13:33:45 c2woody Exp $ */
+/* $Id: dos_classes.cpp,v 1.46 2005-08-23 08:49:57 c2woody Exp $ */
 
 #include <string.h>
 #include <stdlib.h>
@@ -83,7 +83,7 @@ void DOS_InfoBlock::SetLocation(Bit16u segment) {
 	
 	sSave(sDIB,bootDrive,(Bit8u)0);
 	sSave(sDIB,useDwordMov,(Bit8u)1);
-	sSave(sDIB,extendedSize,(Bit16u)0x4000);	// >16mb
+	sSave(sDIB,extendedSize,(Bit16u)(MEM_TotalPages()*4-1024));
 	sSave(sDIB,magicWord,(Bit16u)0x0001);		// dos5+
 
 	sSave(sDIB,sharingCount,(Bit16u)0);