diff --git a/mps/code/ssw3i3mv.c b/mps/code/ssw3i3mv.c
index e09b53ec620..d33bc378e46 100755
--- a/mps/code/ssw3i3mv.c
+++ b/mps/code/ssw3i3mv.c
@@ -1,35 +1,91 @@
-/* ssw3mv.c: STACK SCANNING FOR WIN32 WITH MICROSOFT C
+/* ssw3i3.c: WIN32/INTEL STACK SCANNING
  *
  * $Id$
  * Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
  *
- * This scans the stack and fixes the registers which may contain roots.
- * See <design/thread-manager/>.
+ *  This scans the stack and fixes the registers which may contain
+ *  roots.  See <design/thread-manager/>.
+ *
+ *  The registers edi, esi, ebx are the registers defined to be preserved
+ *  across function calls and therefore may contain roots.
+ *  These are pushed on the stack for scanning.
+ *
+ * ASSUMPTIONS
+ *
+ * .align: The stack pointer is assumed to be aligned on a word
+ * boundary.
  */
 
-#include "mpm.h"
-#include <setjmp.h>
 
-SRCID(ssw3mv, "$Id$");
+#include "mpm.h"
+
+SRCID(ssw3i3, "$Id$");
 
 
 Res StackScan(ScanState ss, Addr *stackBot)
 {
-  jmp_buf jb;
+  Addr *stackTop;
+  Res res;
+  
+  /* NOTE: We would like to use the same `setjmp` trick as ssw3i6mv.c here,
+     to avoid assembler, but this introduces a dependency on the C run-time
+     in Open Dylan on Windows, probably because of ancient build tools.  So
+     I have reverted to the assembler method for now.  RB 2012-09-12 */
 
-  /* We rely on the fact that Microsoft C's setjmp stores the callee-save
-     registers in the jmp_buf. */
-  (void)setjmp(jb);
+  __asm {
+    push edi           /* these registers are the save registers  */
+    push esi           /* and so may contain roots.  They are pushed */
+    push ebx           /* for scanning */
+    mov stackTop, esp  /* stack pointer */
+  }
+  
+  res = StackScanInner(ss, stackBot, stackTop, 3);
 
-  /* These checks will just serve to warn us at compile-time if the
-     setjmp.h header changes to indicate that the registers we want aren't
-     saved any more. */
-  AVER(sizeof(((_JUMP_BUFFER *)jb)->Edi) == sizeof(Addr));
-  AVER(sizeof(((_JUMP_BUFFER *)jb)->Esi) == sizeof(Addr));
-  AVER(sizeof(((_JUMP_BUFFER *)jb)->Ebx) == sizeof(Addr));
+  __asm {
+    add esp, 0xc       /* pop 3 registers to restore the stack pointer */
+  }
 
-  AVER(offsetof(_JUMP_BUFFER, Edi) == offsetof(_JUMP_BUFFER, Ebx) + 4);
-  AVER(offsetof(_JUMP_BUFFER, Esi) == offsetof(_JUMP_BUFFER, Ebx) + 8);
-
-  return StackScanInner(ss, stackBot, (Addr *)&((_JUMP_BUFFER *)jb)->Ebx, 3);
+  return res;
 }
+
+
+/* C. COPYRIGHT AND LICENSE
+ *
+ * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * All rights reserved.  This is an open source license.  Contact
+ * Ravenbrook for commercial licensing options.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * 3. Redistributions in any form must be accompanied by information on how
+ * to obtain complete source code for this software and any accompanying
+ * software that uses this software.  The source code must either be
+ * included in the distribution or be available for no more than the cost
+ * of distribution plus a nominal fee, and must be freely redistributable
+ * under reasonable conditions.  For an executable file, complete source
+ * code means the source code for all modules it contains. It does not
+ * include source code for modules or files that typically accompany the
+ * major components of the operating system on which the executable file
+ * runs.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */