diff --git a/include/dos_inc.h b/include/dos_inc.h
index 892f63f3..3256e64d 100644
--- a/include/dos_inc.h
+++ b/include/dos_inc.h
@@ -16,7 +16,7 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* $Id: dos_inc.h,v 1.79 2009-07-02 18:56:11 c2woody Exp $ */
+/* $Id: dos_inc.h,v 1.80 2009-07-08 20:05:41 c2woody Exp $ */
 
 #ifndef DOSBOX_DOS_INC_H
 #define DOSBOX_DOS_INC_H
@@ -86,7 +86,7 @@ enum { RETURN_EXIT=0,RETURN_CTRLC=1,RETURN_ABORT=2,RETURN_TSR=3};
 #define DOS_SDA_OFS 0
 #define DOS_CDS_SEG 0x108
 #define DOS_FIRST_SHELL 0x118
-#define DOS_MEM_START 0x170		//First Segment that DOS can use
+#define DOS_MEM_START 0x16f		//First Segment that DOS can use
 
 #define DOS_PRIVATE_SEGMENT 0xc800
 #define DOS_PRIVATE_SEGMENT_END 0xd000
diff --git a/src/shell/shell.cpp b/src/shell/shell.cpp
index 5dd268b9..3d317904 100644
--- a/src/shell/shell.cpp
+++ b/src/shell/shell.cpp
@@ -16,7 +16,7 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* $Id: shell.cpp,v 1.99 2009-05-14 18:44:54 qbix79 Exp $ */
+/* $Id: shell.cpp,v 1.100 2009-07-08 20:05:41 c2woody Exp $ */
 
 #include <stdlib.h>
 #include <stdarg.h>
@@ -584,7 +584,7 @@ void SHELL_Init() {
 	pspmcb.SetType(0x4d);
 	DOS_MCB envmcb((Bit16u)(env_seg-1));
 	envmcb.SetPSPSeg(psp_seg);	// MCB of the command shell environment
-	envmcb.SetSize(0x28);
+	envmcb.SetSize(DOS_MEM_START-env_seg);
 	envmcb.SetType(0x4d);
 	
 	/* Setup environment */