diff --git a/mps/code/amcss.c b/mps/code/amcss.c
index 1b32c849769..3f9afba4e82 100644
--- a/mps/code/amcss.c
+++ b/mps/code/amcss.c
@@ -196,7 +196,8 @@ static void test(mps_arena_t arena)
       collections = c;
       report(arena);
 
-      printf("%lu objects (mps_collections says: %lu)\n", objs, c);
+      printf("%lu objects (mps_collections says: %"PRIuLONGEST")\n", objs,
+             (ulongest_t)c);
 
       /* test mps_arena_has_addr */
       {
diff --git a/mps/code/amcsshe.c b/mps/code/amcsshe.c
index 248929240d0..15dd342336c 100644
--- a/mps/code/amcsshe.c
+++ b/mps/code/amcsshe.c
@@ -173,7 +173,8 @@ static void *test(void *arg, size_t s)
 
     if (collections != c) {
       collections = c;
-      printf("\nCollection %lu, %lu objects.\n", c, objs);
+      printf("\nCollection %"PRIuLONGEST", %lu objects.\n",
+             (ulongest_t)c, objs);
       report(arena);
       for (r = 0; r < exactRootsCOUNT; ++r) {
         if (exactRoots[r] != objNULL)
diff --git a/mps/code/apss.c b/mps/code/apss.c
index 8016f9b1aa5..04818600510 100644
--- a/mps/code/apss.c
+++ b/mps/code/apss.c
@@ -43,14 +43,14 @@ static mps_res_t make(mps_addr_t *p, mps_ap_t ap, size_t size)
 
 /* stress -- create a pool of the requested type and allocate in it */
 
-static mps_res_t stress(mps_class_t class, size_t (*size)(unsigned long i),
+static mps_res_t stress(mps_class_t class, size_t (*size)(size_t i),
                         mps_arena_t arena, ...)
 {
   mps_res_t res = MPS_RES_OK;
   mps_pool_t pool;
   mps_ap_t ap;
   va_list arg;
-  unsigned long i, k;
+  size_t i, k;
   int *ps[testSetSIZE];
   size_t ss[testSetSIZE];
 
@@ -78,7 +78,7 @@ static mps_res_t stress(mps_class_t class, size_t (*size)(unsigned long i),
   for (k=0; k<testLOOPS; ++k) {
     /* shuffle all the objects */
     for (i=0; i<testSetSIZE; ++i) {
-      unsigned long j = rnd()%(testSetSIZE-i);
+      size_t j = rnd()%(testSetSIZE-i);
       void *tp;
       size_t ts;
      
@@ -114,7 +114,7 @@ allocFail:
 /* randomSizeAligned -- produce sizes both large and small,
  * aligned by platform alignment */
 
-static size_t randomSizeAligned(unsigned long i)
+static size_t randomSizeAligned(size_t i)
 {
   size_t maxSize = 2 * 160 * 0x2000;
   /* Reduce by a factor of 2 every 10 cycles.  Total allocation about 40 MB. */
diff --git a/mps/code/awlut.c b/mps/code/awlut.c
index a8d96d930e0..e5dbd64a47e 100644
--- a/mps/code/awlut.c
+++ b/mps/code/awlut.c
@@ -118,7 +118,7 @@ static mps_word_t *alloc_string(const char *s, mps_ap_t ap)
  * .assume.dylan-obj
  */
 
-static mps_word_t *alloc_table(unsigned long n, mps_ap_t ap)
+static mps_word_t *alloc_table(size_t n, mps_ap_t ap)
 {
   size_t objsize;
   void *p;
@@ -127,7 +127,7 @@ static mps_word_t *alloc_table(unsigned long n, mps_ap_t ap)
   objsize = (3 + n) * sizeof(mps_word_t);
   objsize = size_tAlignUp(objsize, MPS_PF_ALIGN);
   do {
-    unsigned long i;
+    size_t i;
 
     die(mps_reserve(&p, ap, objsize), "Reserve Table\n");
     object = p;
@@ -145,7 +145,7 @@ static mps_word_t *alloc_table(unsigned long n, mps_ap_t ap)
 /* gets the nth slot from a table
  * .assume.dylan-obj
  */
-static mps_word_t *table_slot(mps_word_t *table, unsigned long n)
+static mps_word_t *table_slot(mps_word_t *table, size_t n)
 {
   return (mps_word_t *)table[3+n];
 }
@@ -154,8 +154,7 @@ static mps_word_t *table_slot(mps_word_t *table, unsigned long n)
 /* sets the nth slot in a table
  * .assume.dylan-obj
  */
-static void set_table_slot(mps_word_t *table,
-                           unsigned long n, mps_word_t *p)
+static void set_table_slot(mps_word_t *table, size_t n, mps_word_t *p)
 {
   cdie(table[0] == (mps_word_t)table_wrapper, "set_table_slot");
   table[3+n] = (mps_word_t)p;
@@ -182,7 +181,7 @@ static void test(mps_arena_t arena,
   mps_word_t *exacttable;
   mps_word_t *preserve[TABLE_SLOTS];    /* preserves objects in the weak */
                                         /* table by referring to them */
-  unsigned long i, j;
+  size_t i, j;
   void *p;
 
   exacttable = alloc_table(TABLE_SLOTS, exactap);
diff --git a/mps/code/awluthe.c b/mps/code/awluthe.c
index be07c7b48f6..fa883a30487 100644
--- a/mps/code/awluthe.c
+++ b/mps/code/awluthe.c
@@ -130,7 +130,7 @@ static mps_word_t *alloc_table(unsigned long n, mps_ap_t ap)
   objsize = (3 + n) * sizeof(mps_word_t);
   objsize = size_tAlignUp(objsize, MPS_PF_ALIGN);
   do {
-    unsigned long i;
+    size_t i;
 
     die(mps_reserve(&p, ap, objsize + headerSIZE), "Reserve Table\n");
     object = (mps_word_t *)((char *)p + headerSIZE);
@@ -150,7 +150,7 @@ static mps_word_t *alloc_table(unsigned long n, mps_ap_t ap)
 /* gets the nth slot from a table
  * .assume.dylan-obj
  */
-static mps_word_t *table_slot(mps_word_t *table, unsigned long n)
+static mps_word_t *table_slot(mps_word_t *table, size_t n)
 {
   return (mps_word_t *)table[3+n];
 }
@@ -159,8 +159,7 @@ static mps_word_t *table_slot(mps_word_t *table, unsigned long n)
 /* sets the nth slot in a table
  * .assume.dylan-obj
  */
-static void set_table_slot(mps_word_t *table,
-                           unsigned long n, mps_word_t *p)
+static void set_table_slot(mps_word_t *table, size_t n, mps_word_t *p)
 {
   cdie(table[0] == (mps_word_t)table_wrapper, "set_table_slot");
   table[3+n] = (mps_word_t)p;
@@ -187,7 +186,7 @@ static void test(mps_arena_t arena,
   mps_word_t *exacttable;
   mps_word_t *preserve[TABLE_SLOTS];    /* preserves objects in the weak */
                                         /* table by referring to them */
-  unsigned long i, j;
+  size_t i, j;
   void *p;
 
   exacttable = alloc_table(TABLE_SLOTS, exactap);
diff --git a/mps/code/config.h b/mps/code/config.h
index 0a1dc4a6a2e..c785cf7f949 100644
--- a/mps/code/config.h
+++ b/mps/code/config.h
@@ -212,13 +212,16 @@
 
 
 /* Suppress Pelles C warnings at warning level 2 */
-/* Essentially the same settings are done in testlib.h. */
+/* Some of the same settings are done in testlib.h. */
 
 #ifdef MPS_BUILD_PC
 
 /* "Unreachable code" (AVER, if condition is constantly true). */
 #pragma warn(disable: 2154)
 
+/* "Consider changing type to 'size_t' for loop variable" */
+#pragma warn(disable: 2804)
+
 #endif /* MPS_BUILD_PC */
 
 
diff --git a/mps/code/eventrep.c b/mps/code/eventrep.c
index c2f611f7070..66988cf2e24 100644
--- a/mps/code/eventrep.c
+++ b/mps/code/eventrep.c
@@ -31,7 +31,7 @@
 #include "mpstd.h"
 
 
-#ifdef MPS_PF_W3I6MV
+#if defined(MPS_OS_w3) && defined(MPS_ARCH_I6)
 #define PRIuLONGEST "llu"
 #define PRIXPTR     "016llX"
 typedef unsigned long long ulongest_t;
diff --git a/mps/code/exposet0.c b/mps/code/exposet0.c
index a3eb7266e1a..11e78ad29cb 100644
--- a/mps/code/exposet0.c
+++ b/mps/code/exposet0.c
@@ -185,7 +185,8 @@ static void *test(void *arg, size_t s)
 
     if (collections != c) {
       collections = c;
-      printf("\nCollection %lu started, %lu objects.\n", c, objs);
+      printf("\nCollection %"PRIuLONGEST" started, %lu objects.\n",
+             (ulongest_t)c, objs);
 
       report(arena);
       for (i = 0; i < exactRootsCOUNT; ++i) {
diff --git a/mps/code/expt825.c b/mps/code/expt825.c
index 8c8d1e79a3d..459452bc722 100644
--- a/mps/code/expt825.c
+++ b/mps/code/expt825.c
@@ -202,8 +202,10 @@ static void *test(void *arg, size_t s)
                   testlib_unused(obj);
           }
           finals += final_this_time;
-          printf("%lu objects finalized: total %lu of %lu\n",
-                 final_this_time, finals, object_count);
+          printf("%"PRIuLONGEST" objects finalized: total %"PRIuLONGEST
+                 " of %"PRIuLONGEST"\n",
+                 (ulongest_t)final_this_time, (ulongest_t)finals,
+                 (ulongest_t)object_count);
   }
 
   object_count = 0;
@@ -243,8 +245,10 @@ static void *test(void *arg, size_t s)
                   testlib_unused(obj);
           }
           finals += final_this_time;
-          printf("%lu objects finalized: total %lu of %lu\n",
-                 final_this_time, finals, object_count);
+          printf("%"PRIuLONGEST" objects finalized: total %"PRIuLONGEST
+                 " of %"PRIuLONGEST"\n",
+                 (ulongest_t)final_this_time, (ulongest_t)finals,
+                 (ulongest_t)object_count);
   }
 
   mps_ap_destroy(ap);
diff --git a/mps/code/fbmtest.c b/mps/code/fbmtest.c
index e26c9f26224..f98c49032a9 100644
--- a/mps/code/fbmtest.c
+++ b/mps/code/fbmtest.c
@@ -605,10 +605,14 @@ extern int main(int argc, char *argv[])
 
   mps_arena_destroy(arena);
 
-  printf("\nNumber of allocations attempted: %ld\n", NAllocateTried);
-  printf("Number of allocations succeeded: %ld\n", NAllocateSucceeded);
-  printf("Number of deallocations attempted: %ld\n", NDeallocateTried);
-  printf("Number of deallocations succeeded: %ld\n", NDeallocateSucceeded);
+  printf("\nNumber of allocations attempted: %"PRIuLONGEST"\n",
+         (ulongest_t)NAllocateTried);
+  printf("Number of allocations succeeded: %"PRIuLONGEST"\n",
+         (ulongest_t)NAllocateSucceeded);
+  printf("Number of deallocations attempted: %"PRIuLONGEST"\n",
+         (ulongest_t)NDeallocateTried);
+  printf("Number of deallocations succeeded: %"PRIuLONGEST"\n",
+         (ulongest_t)NDeallocateSucceeded);
   printf("%s: Conclusion: Failed to find any defects.\n", argv[0]);
   return 0;
 }
diff --git a/mps/code/finalcv.c b/mps/code/finalcv.c
index daed57c7311..e8f7e251a6e 100644
--- a/mps/code/finalcv.c
+++ b/mps/code/finalcv.c
@@ -186,7 +186,8 @@ static void *test(void *arg, size_t s)
       mps_message_finalization_ref(&objaddr, arena, message);
       obj = objaddr;
       objind = dylan_int_int(obj[vectorSLOT]);
-      printf("Finalizing: object %lu at %p\n", objind, objaddr);
+      printf("Finalizing: object %"PRIuLONGEST" at %p\n",
+             (ulongest_t)objind, objaddr);
       /* <design/poolmrg/#test.promise.ut.final.check> */
       cdie(root[objind] == NULL, "finalized live");
       cdie(state[objind] == finalizableSTATE, "finalized dead");
diff --git a/mps/code/finaltest.c b/mps/code/finaltest.c
index a6c23aebfd1..ee7a55ee3e7 100644
--- a/mps/code/finaltest.c
+++ b/mps/code/finaltest.c
@@ -188,7 +188,8 @@ static void *test(void *arg, size_t s)
                   ++ final_this_time;
           }
           finals += final_this_time;
-          printf("%lu objects finalized: total %lu of %lu\n",
+          printf("%"PRIuLONGEST" objects finalized: total %"PRIuLONGEST
+                 " of %"PRIuLONGEST"\n",
                  final_this_time, finals, object_count);
   }
 
@@ -226,7 +227,8 @@ static void *test(void *arg, size_t s)
                   ++ final_this_time;
           }
           finals += final_this_time;
-          printf("%lu objects finalized: total %lu of %lu\n",
+          printf("%"PRIuLONGEST" objects finalized: total %"PRIuLONGEST
+                 " of %"PRIuLONGEST"\n",
                  final_this_time, finals, object_count);
   }
 
diff --git a/mps/code/fmtdy.c b/mps/code/fmtdy.c
index 498f8811635..758a7f4ebbb 100644
--- a/mps/code/fmtdy.c
+++ b/mps/code/fmtdy.c
@@ -493,15 +493,15 @@ extern mps_res_t dylan_scan1(mps_ss_t mps_ss, mps_addr_t *object_io)
       break;
 
       case 4:                   /* non-word */
-      es = (vh & 0xff) >> 3;
-      vb = (vh >> 16) & 0xff;
+      es = (unsigned)(vh & 0xff) >> 3;
+      vb = (unsigned)((vh >> 16) & 0xff);
       vt += vb;
       p += NONWORD_LENGTH(vt, es);
       break;
 
       case 5:                   /* stretchy non-word */
-      es = (vh & 0xff) >> 3;
-      vb = (vh >> 16) & 0xff;
+      es = (unsigned)(vh & 0xff) >> 3;
+      vb = (unsigned)((vh >> 16) & 0xff);
       vt += vb;
       p += NONWORD_LENGTH(vt, es) + 1;
       notreached();             /* DW doesn't create them yet */
@@ -678,8 +678,8 @@ static mps_addr_t dylan_skip(mps_addr_t object)
 
     if((vf & 6) == 4)           /* non-word */
     {
-      es = (vh & 0xff) >> 3;
-      vb = (vh >> 16) & 0xff;
+      es = (unsigned)(vh & 0xff) >> 3;
+      vb = (unsigned)((vh >> 16) & 0xff);
       vt += vb;
       p += NONWORD_LENGTH(vt, es);
     }
diff --git a/mps/code/locbwcss.c b/mps/code/locbwcss.c
index 3bc674c7d68..e37f59cbc30 100644
--- a/mps/code/locbwcss.c
+++ b/mps/code/locbwcss.c
@@ -110,7 +110,7 @@ static void poolStatInit(PoolStat stat, mps_pool_t pool, size_t objSize)
 static void allocMultiple(PoolStat stat)
 {
   mps_addr_t objects[allocsPerIteration];
-  int i;
+  size_t i;
 
   /* allocate a few objects, and record stats for them */
   for (i = 0; i < allocsPerIteration; i++) {
diff --git a/mps/code/locusss.c b/mps/code/locusss.c
index b399e58e8da..22a35ab6e4e 100644
--- a/mps/code/locusss.c
+++ b/mps/code/locusss.c
@@ -110,7 +110,7 @@ static void poolStatInit(PoolStat stat, mps_pool_t pool, size_t objSize)
 static mps_res_t allocMultiple(PoolStat stat)
 {
   mps_addr_t objects[contigAllocs];
-  int i;
+  size_t i;
 
   /* allocate a few objects, and record stats for them */
   for (i = 0; i < contigAllocs; i++) {
diff --git a/mps/code/mpmss.c b/mps/code/mpmss.c
index b2a48347382..9e592a7513c 100644
--- a/mps/code/mpmss.c
+++ b/mps/code/mpmss.c
@@ -30,13 +30,13 @@ extern mps_class_t PoolClassMFS(void);
 
 /* stress -- create a pool of the requested type and allocate in it */
 
-static mps_res_t stress(mps_class_t class, size_t (*size)(int i),
+static mps_res_t stress(mps_class_t class, size_t (*size)(size_t i),
                         mps_arena_t arena, ...)
 {
   mps_res_t res;
   mps_pool_t pool;
   va_list arg;
-  int i, k;
+  size_t i, k;
   int *ps[testSetSIZE];
   size_t ss[testSetSIZE];
 
@@ -94,7 +94,7 @@ static mps_res_t stress(mps_class_t class, size_t (*size)(int i),
 
 /* randomSize -- produce sizes both latge and small */
 
-static size_t randomSize(int i)
+static size_t randomSize(size_t i)
 {
   /* Make the range large enough to span three pages in the segment table: */
   /* 160 segments/page, page size max 0x2000. */
@@ -106,7 +106,7 @@ static size_t randomSize(int i)
 
 /* randomSize8 -- produce sizes both latge and small, 8-byte aligned */
 
-static size_t randomSize8(int i)
+static size_t randomSize8(size_t i)
 {
   size_t maxSize = 2 * 160 * 0x2000;
   /* Reduce by a factor of 2 every 10 cycles.  Total allocation about 40 MB. */
diff --git a/mps/code/mps.c b/mps/code/mps.c
index ce910bad927..0a8f29be9ba 100644
--- a/mps/code/mps.c
+++ b/mps/code/mps.c
@@ -229,6 +229,21 @@
 #include "spw3i3.c"     /* 32-bit Intel stack probe */
 #include "mpsiw3.c"     /* Windows interface layer extras */
 
+/* Windows on 64-bit Intel with Pelles C */
+
+#elif defined(MPS_PF_W3I6PC)
+
+#include "lockw3.c"     /* Windows locks */
+#include "thw3.c"       /* Windows threading */
+#include "thw3i6.c"     /* Windows on 64-bit Intel thread stack scan */
+#include "vmw3.c"       /* Windows virtual memory */
+#include "protw3.c"     /* Windows protection */
+#include "proti6.c"     /* 64-bit Intel mutator context decoding */
+#include "prmci6w3.c"   /* Windows on 64-bit Intel mutator context */
+#include "ssw3i6pc.c"   /* Windows on 64-bit stack scan for Pelles C */
+#include "spw3i6.c"     /* 64-bit Intel stack probe */
+#include "mpsiw3.c"     /* Windows interface layer extras */
+
 #else
 
 #error "Unknown platform -- can't determine platform specific parts."
diff --git a/mps/code/mpstd.h b/mps/code/mpstd.h
index 891d5979647..1306281224b 100644
--- a/mps/code/mpstd.h
+++ b/mps/code/mpstd.h
@@ -97,6 +97,27 @@
 #define MPS_PF_ALIGN    8
 
 
+/* PellesC version 7.00.25 with /Ze option (Microsoft compatibility mode)
+ * and /Tarm64-coff (Create a COFF object file for a X64 processor).
+ * Help node "Predefined preprocessor symbols (POCC)"
+ */
+
+#elif defined(__POCC__) && defined(_WIN32) && defined(_WIN64) && defined(_M_X64)
+#if defined(CONFIG_PF_STRING) && ! defined(CONFIG_PF_W3I6PC)
+#error "specified CONFIG_PF_... inconsistent with detected w3i6pc"
+#endif
+#define MPS_PF_W3I6PC
+#define MPS_PF_STRING   "w3i6pc"
+#define MPS_OS_W3
+#define MPS_ARCH_I6
+#define MPS_BUILD_PC
+#define MPS_T_WORD      unsigned __int64
+#define MPS_T_ULONGEST  unsigned __int64
+#define MPS_WORD_WIDTH  64
+#define MPS_WORD_SHIFT  6
+#define MPS_PF_ALIGN    16
+
+
 /* GCC 4.0.1 (As supplied by Apple on Mac OS X 10.4.8 on an Intel Mac),
  * gcc -E -dM
  * And above for xcppgc.
diff --git a/mps/code/qs.c b/mps/code/qs.c
index 2e573d0840b..2ccc9423184 100644
--- a/mps/code/qs.c
+++ b/mps/code/qs.c
@@ -186,7 +186,7 @@ static void swap(void)
 
 static void makerndlist(unsigned l)
 {
-  unsigned i;
+  size_t i;
   mps_word_t r;
   mps_addr_t addr;
 
diff --git a/mps/code/replay.c b/mps/code/replay.c
index 974ce5dcd07..0069e7415c1 100644
--- a/mps/code/replay.c
+++ b/mps/code/replay.c
@@ -21,7 +21,7 @@
 #include "mpstd.h"
 
 
-#ifdef MPS_PF_W3I6MV
+#if defined(MPS_OS_W3) && defined(MPS_ARCH_I6)
 #define PRIuLONGEST "llu"
 #define PRIXPTR     "016llX"
 typedef unsigned long long ulongest_t;
diff --git a/mps/code/sacss.c b/mps/code/sacss.c
index d48b41708d8..bfb0725ed47 100644
--- a/mps/code/sacss.c
+++ b/mps/code/sacss.c
@@ -47,13 +47,13 @@ static mps_res_t make(mps_addr_t *p, mps_sac_t sac, size_t size)
 
 static mps_res_t stress(mps_class_t class,
                         size_t classes_count, mps_sac_classes_s *classes,
-                        size_t (*size)(int i), mps_arena_t arena, ...)
+                        size_t (*size)(size_t i), mps_arena_t arena, ...)
 {
   mps_res_t res;
   mps_pool_t pool;
   mps_sac_t sac;
   va_list arg;
-  int i, k;
+  size_t i, k;
   int *ps[testSetSIZE];
   size_t ss[testSetSIZE];
 
@@ -127,7 +127,7 @@ static mps_res_t stress(mps_class_t class,
 
 /* randomSize8 -- produce sizes both latge and small */
 
-static size_t randomSize8(int i)
+static size_t randomSize8(size_t i)
 {
   size_t maxSize = 2 * 160 * 0x2000;
   size_t size;
diff --git a/mps/code/spw3i6.c b/mps/code/spw3i6.c
index 10404d4559e..29b1f8b8dcf 100644
--- a/mps/code/spw3i6.c
+++ b/mps/code/spw3i6.c
@@ -22,7 +22,7 @@
 
 void StackProbe(Size depth)
 {
-  _alloca(depth*sizeof(Word));
+  (void)_alloca(depth*sizeof(Word));
 }
 
 
diff --git a/mps/code/ssw3i6pc.c b/mps/code/ssw3i6pc.c
new file mode 100644
index 00000000000..c58e88f846a
--- /dev/null
+++ b/mps/code/ssw3i6pc.c
@@ -0,0 +1,143 @@
+/* ssw3i6pc.c: STACK SCANNING FOR WIN32 WITH PELLES C
+ *
+ * $Id$
+ * Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
+ *
+ * This scans the stack and fixes the registers which may contain roots.
+ * See <design/thread-manager/>.
+ *
+ * .assume.ms-compat: We rely on the fact that Pelles C's setjmp stores
+ * the callee-save registers in the jmp_buf and is compatible with Microsoft
+ * C.  The Pelles C 7.00 setjmp.h header has a comment "MS compatible".  See
+ * also "Is Pelles C's jmp_buf compatible with Microsoft C's?"
+ * <http://forum.pellesc.de/index.php?topic=5464>
+ *
+ * REFERENCES
+ *
+ * "Overview of x64 Calling Conventions"; MSDN; Microsoft Corporation;
+ * <http://msdn.microsoft.com/en-us/library/ms235286%28v=vs.100%29.aspx>.
+ *
+ * "Caller/Callee Saved Registers"; MSDN; Microsoft Corporation;
+ * <http://msdn.microsoft.com/en-us/library/6t169e9c%28v=vs.100%29.aspx>.
+ *
+ * "Register Usage"; MSDN; Microsoft Corporation;
+ * <http://msdn.microsoft.com/en-us/library/9z1stfyw%28v=vs.100%29.aspx>.
+ *
+ * "Calling conventions for different C++ compilers and operating systems";
+ * Agner Fog; Copenhagen University College of Engineering; 2012-02-29;
+ * <http://agner.org./optimize/calling_conventions.pdf>.
+ */
+
+#include "mpm.h"
+#include <setjmp.h>
+
+SRCID(ssw3i6pc, "$Id$");
+
+
+/* This definition isn't in the Pelles C headers, so we reproduce it here.
+ * See .assume.ms-compat. */
+
+typedef /* _CRT_ALIGN(16) */ struct _SETJMP_FLOAT128 {
+    unsigned __int64 Part[2];
+} SETJMP_FLOAT128;
+
+typedef struct _JUMP_BUFFER {
+    unsigned __int64 Frame;
+    unsigned __int64 Rbx;
+    unsigned __int64 Rsp;
+    unsigned __int64 Rbp;
+    unsigned __int64 Rsi;
+    unsigned __int64 Rdi;
+    unsigned __int64 R12;
+    unsigned __int64 R13;
+    unsigned __int64 R14;
+    unsigned __int64 R15;
+    unsigned __int64 Rip;
+    unsigned __int64 Spare;
+    
+    SETJMP_FLOAT128 Xmm6;
+    SETJMP_FLOAT128 Xmm7;
+    SETJMP_FLOAT128 Xmm8;
+    SETJMP_FLOAT128 Xmm9;
+    SETJMP_FLOAT128 Xmm10;
+    SETJMP_FLOAT128 Xmm11;
+    SETJMP_FLOAT128 Xmm12;
+    SETJMP_FLOAT128 Xmm13;
+    SETJMP_FLOAT128 Xmm14;
+    SETJMP_FLOAT128 Xmm15;
+} _JUMP_BUFFER;
+
+
+Res StackScan(ScanState ss, Addr *stackBot)
+{
+  jmp_buf jb;
+
+  /* We rely on the fact that Pelles C's setjmp stores the callee-save
+     registers in the jmp_buf. */
+  (void)setjmp(jb);
+
+  /* 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)->Rdi) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->Rsi) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->Rbp) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->R12) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->R13) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->R14) == sizeof(Addr));
+  AVER(sizeof(((_JUMP_BUFFER *)jb)->R15) == sizeof(Addr));
+
+  /* The layout of the jmp_buf forces us to harmlessly scan Rsp as well. */
+  AVER(offsetof(_JUMP_BUFFER, Rsp) == offsetof(_JUMP_BUFFER, Rbx) + 8);
+  AVER(offsetof(_JUMP_BUFFER, Rbp) == offsetof(_JUMP_BUFFER, Rbx) + 16);
+  AVER(offsetof(_JUMP_BUFFER, Rsi) == offsetof(_JUMP_BUFFER, Rbx) + 24);
+  AVER(offsetof(_JUMP_BUFFER, Rdi) == offsetof(_JUMP_BUFFER, Rbx) + 32);
+  AVER(offsetof(_JUMP_BUFFER, R12) == offsetof(_JUMP_BUFFER, Rbx) + 40);
+  AVER(offsetof(_JUMP_BUFFER, R13) == offsetof(_JUMP_BUFFER, Rbx) + 48);
+  AVER(offsetof(_JUMP_BUFFER, R14) == offsetof(_JUMP_BUFFER, Rbx) + 56);
+  AVER(offsetof(_JUMP_BUFFER, R15) == offsetof(_JUMP_BUFFER, Rbx) + 64);
+
+  return StackScanInner(ss, stackBot, (Addr *)&((_JUMP_BUFFER *)jb)->Rbx, 9);
+}
+
+
+/* C. COPYRIGHT AND LICENSE
+ *
+ * Copyright (C) 2001-2014 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.
+ */
diff --git a/mps/code/steptest.c b/mps/code/steptest.c
index b6e08995125..4d6353e78df 100644
--- a/mps/code/steptest.c
+++ b/mps/code/steptest.c
@@ -420,8 +420,8 @@ static void *test(void *arg, size_t s)
     printf("Collection statistics:\n");
     printf("  %"PRIuLONGEST" collections\n", (ulongest_t)collections);
     printf("  %"PRIuLONGEST" bytes condemned.\n", (ulongest_t)condemned);
-    printf("  %lu bytes not condemned.\n",
-           (unsigned long)not_condemned);
+    printf("  %"PRIuLONGEST" bytes not condemned.\n",
+           (ulongest_t)not_condemned);
     printf("  %"PRIuLONGEST" bytes survived.\n", (ulongest_t)live);
     if (condemned) {
         printf("  Mortality %5.2f%%.\n",
@@ -430,10 +430,10 @@ static void *test(void *arg, size_t s)
                ((double)condemned/(condemned + not_condemned)) * 100.0);
     }
     if (collections) {
-        printf("  Condemned per collection %lu bytes.\n",
-               (unsigned long)condemned/collections);
-        printf("  Reclaimed per collection %lu bytes.\n",
-               (unsigned long)(condemned - live)/collections);
+        printf("  Condemned per collection %"PRIuLONGEST" bytes.\n",
+               (ulongest_t)condemned/collections);
+        printf("  Reclaimed per collection %"PRIuLONGEST" bytes.\n",
+               (ulongest_t)(condemned - live)/collections);
     }
 
     printf("Allocation statistics:\n");
diff --git a/mps/code/teletest.c b/mps/code/teletest.c
index 1e0dca6a53e..312237f5251 100644
--- a/mps/code/teletest.c
+++ b/mps/code/teletest.c
@@ -19,19 +19,10 @@ SRCID(teletest, "$Id$");
 
 static mps_arena_t arena;
 
-
+#define WORD_FORMAT "%" PRIwWORD PRIuLONGEST
 #define MAX_ARGS 3
 #define INPUT_BUFFER_SIZE 512
 
-#if (MPS_WORD_WIDTH == 32)
-#define WORD_FORMAT "0x%08lx"
-#elif (MPS_WORD_WIDTH == 64)
-#define WORD_FORMAT "0x%016lx"
-#else
-#error "Unrecognized word width"
-#endif
-
-
 static mps_word_t args[MAX_ARGS];
 static char *stringArg;
 static Count argCount;
@@ -43,7 +34,8 @@ static void callControl(mps_word_t reset, mps_word_t flip)
   old = mps_telemetry_control(reset, flip);
   new = mps_telemetry_control((mps_word_t)0, (mps_word_t)0);
 
-  (void)printf(WORD_FORMAT " -> " WORD_FORMAT "\n", old, new);
+  (void)printf(WORD_FORMAT " -> " WORD_FORMAT "\n",
+               (ulongest_t)old, (ulongest_t)new);
 }
 
 
@@ -58,7 +50,7 @@ static void doRead(void)
   mps_word_t old;
   old = mps_telemetry_control((mps_word_t)0, (mps_word_t)0);
       
-  (void)printf(WORD_FORMAT "\n", old);
+  (void)printf(WORD_FORMAT "\n", (ulongest_t)old);
 }
 
 
@@ -85,7 +77,7 @@ static void doIntern(void)
   mps_word_t id;
 
   id = mps_telemetry_intern(stringArg);
-  (void)printf(WORD_FORMAT "\n", id);
+  (void)printf(WORD_FORMAT "\n", (ulongest_t)id);
 }
 
 static void doLabel(void)
diff --git a/mps/code/testlib.h b/mps/code/testlib.h
index aff3c108351..6dea9beae75 100644
--- a/mps/code/testlib.h
+++ b/mps/code/testlib.h
@@ -101,7 +101,7 @@
 #error "How many beans make five?"
 #endif
 
-#ifdef MPS_PF_W3I6MV
+#if defined(MPS_OS_W3) && defined(MPS_ARCH_I6)
 #define PRIuLONGEST "llu"
 #define SCNuLONGEST "llu"
 #define SCNXLONGEST "llX"
diff --git a/mps/code/w3i6pc.nmk b/mps/code/w3i6pc.nmk
new file mode 100644
index 00000000000..fd3f798a9b5
--- /dev/null
+++ b/mps/code/w3i6pc.nmk
@@ -0,0 +1,175 @@
+# -*- makefile -*-
+#
+# w3i6pc.nmk: NMAKE FILE FOR WINDOWS/x64/PELLES C
+#
+# $Id: //info.ravenbrook.com/project/mps/branch/2014-03-21/pellesc/code/w3i6pc.nmk#1 $
+# Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
+
+PFM = w3i6pc
+
+# /Gs appears to be necessary to suppress stack checks.  Stack checks
+# (if not suppressed) generate a dependency on the C library, __chkesp,
+# which causes the linker step to fail when building the DLL, mpsdy.dll.
+PFMDEFS = /DCONFIG_PF_STRING="w3i6pc" /DCONFIG_PF_W3I6PC /DWIN32 /D_WINDOWS
+
+!INCLUDE commpre.nmk
+!INCLUDE pc.nmk
+
+CFLAGSCOMMONPRE = $(CFLAGSCOMMONPRE) /Tamd64-coff
+
+# MPM sources: core plus platform-specific.
+MPM = $(MPMCOMMON) <proti6> <prmci6w3> <spw3i6> <ssw3i6pc> <thw3i6>
+
+
+
+# Source to object file mappings and CFLAGS amalgamation
+#
+# %%VARIETY %%PART: When adding a new variety or part, add new macros which
+# expand to the files included in the part for each variety
+#
+# %%VARIETY: When adding a new variety, add a CFLAGS macro which expands to
+# the flags that that variety should use when compiling C.  And a LINKFLAGS
+# macro which expands to the flags that the variety should use when building
+# executables.  And a LIBFLAGS macro which expands to the flags that the
+# variety should use when building libraries
+
+!IF "$(VARIETY)" == "hot"
+CFLAGS=$(CFLAGSCOMMONPRE) $(CFHOT) $(CFLAGSCOMMONPOST)
+CFLAGSSQL=$(CFLAGSSQLPRE) $(CFHOT) $(CFLAGSSQLPOST)
+LINKFLAGS=$(LINKFLAGSCOMMON) $(LFHOT)
+LIBFLAGS=$(LIBFLAGSCOMMON) $(LIBFLAGSHOT)
+MPMOBJ0 = $(MPM:<=w3i6pc\hot\)
+PLINTHOBJ0 = $(PLINTH:<=w3i6pc\hot\)
+AMSOBJ0 = $(AMS:<=w3i6pc\hot\)
+AMCOBJ0 = $(AMC:<=w3i6pc\hot\)
+AWLOBJ0 = $(AWL:<=w3i6pc\hot\)
+LOOBJ0 = $(LO:<=w3i6pc\hot\)
+SNCOBJ0 = $(SNC:<=w3i6pc\hot\)
+MVFFOBJ0 = $(MVFF:<=w3i6pc\hot\)
+DWOBJ0 = $(DW:<=w3i6pc\hot\)
+FMTTESTOBJ0 = $(FMTTEST:<=w3i6pc\hot\)
+POOLNOBJ0 = $(POOLN:<=w3i6pc\hot\)
+TESTLIBOBJ0 = $(TESTLIB:<=w3i6pc\hot\)
+
+!ELSEIF "$(VARIETY)" == "cool"
+CFLAGS=$(CFLAGSCOMMONPRE) $(CFCOOL) $(CFLAGSCOMMONPOST)
+CFLAGSSQL=$(CFLAGSSQLPRE) $(CFCOOL) $(CFLAGSSQLPOST)
+LINKFLAGS=$(LINKFLAGSCOMMON) $(LFCOOL)
+LIBFLAGS=$(LIBFLAGSCOMMON) $(LIBFLAGSCOOL)
+MPMOBJ0 = $(MPM:<=w3i6pc\cool\)
+PLINTHOBJ0 = $(PLINTH:<=w3i6pc\cool\)
+AMSOBJ0 = $(AMS:<=w3i6pc\cool\)
+AMCOBJ0 = $(AMC:<=w3i6pc\cool\)
+AWLOBJ0 = $(AWL:<=w3i6pc\cool\)
+LOOBJ0 = $(LO:<=w3i6pc\cool\)
+SNCOBJ0 = $(SNC:<=w3i6pc\cool\)
+MVFFOBJ0 = $(MVFF:<=w3i6pc\cool\)
+DWOBJ0 = $(DW:<=w3i6pc\cool\)
+FMTTESTOBJ0 = $(FMTTEST:<=w3i6pc\cool\)
+POOLNOBJ0 = $(POOLN:<=w3i6pc\cool\)
+TESTLIBOBJ0 = $(TESTLIB:<=w3i6pc\cool\)
+
+!ELSEIF "$(VARIETY)" == "rash"
+CFLAGS=$(CFLAGSCOMMONPRE) $(CFRASH) $(CFLAGSCOMMONPOST)
+CFLAGSSQL=$(CFLAGSSQLPRE) $(CFRASH) $(CFLAGSSQLPOST)
+LINKFLAGS=$(LINKFLAGSCOMMON) $(LFRASH)
+LIBFLAGS=$(LIBFLAGSCOMMON) $(LIBFLAGSRASH)
+MPMOBJ0 = $(MPM:<=w3i6pc\rash\)
+PLINTHOBJ0 = $(PLINTH:<=w3i6pc\rash\)
+AMSOBJ0 = $(AMS:<=w3i6pc\rash\)
+AMCOBJ0 = $(AMC:<=w3i6pc\rash\)
+AWLOBJ0 = $(AWL:<=w3i6pc\rash\)
+LOOBJ0 = $(LO:<=w3i6pc\rash\)
+SNCOBJ0 = $(SNC:<=w3i6pc\rash\)
+MVFFOBJ0 = $(MVFF:<=w3i6pc\rash\)
+DWOBJ0 = $(DW:<=w3i6pc\rash\)
+FMTTESTOBJ0 = $(FMTTEST:<=w3i6pc\rash\)
+POOLNOBJ0 = $(POOLN:<=w3i6pc\rash\)
+TESTLIBOBJ0 = $(TESTLIB:<=w3i6pc\rash\)
+
+#!ELSEIF "$(VARIETY)" == "cv"
+#CFLAGS=$(CFLAGSCOMMON) $(CFCV)
+#LINKFLAGS=$(LINKFLAGSCOMMON) $(LFCV)
+#LIBFLAGS=$(LIBFLAGSCOMMON) $(LIBFLAGSCV)
+#MPMOBJ0 = $(MPM:<=w3i6pc\cv\)
+#MPMOBJ = $(MPMOBJ0:>=.obj)
+#PLINTHOBJ0 = $(PLINTH:<=w3i6pc\cv\)
+#PLINTHOBJ = $(PLINTHOBJ0:>=.obj)
+#AMSOBJ0 = $(AMS:<=w3i6pc\cv\)
+#AMSOBJ = $(AMSOBJ0:>=.obj)
+#AMCOBJ0 = $(AMC:<=w3i6pc\cv\)
+#AMCOBJ = $(AMCOBJ0:>=.obj)
+#AWLOBJ0 = $(AWL:<=w3i6pc\cv\)
+#AWLOBJ = $(AWLOBJ0:>=.obj)
+#LOOBJ0 = $(LO:<=w3i6pc\cv\)
+#LOOBJ = $(LOOBJ0:>=.obj)
+#SNCOBJ0 = $(SNC:<=w3i6pc\cv\)
+#SNCOBJ = $(SNCOBJ0:>=.obj)
+#DWOBJ0 = $(DW:<=w3i6pc\cv\)
+#DWOBJ = $(DWOBJ0:>=.obj)
+#POOLNOBJ0 = $(POOLN:<=w3i6pc\cv\)
+#POOLNOBJ = $(POOLNOBJ0:>=.obj)
+#TESTLIBOBJ0 = $(TESTLIB:<=w3i6pc\cv\)
+#TESTLIBOBJ = $(TESTLIBOBJ0:>=.obj)
+
+!ENDIF
+
+# %%PART: When adding a new part, add new macros which expand to the object
+# files included in the part
+
+MPMOBJ = $(MPMOBJ0:>=.obj)
+PLINTHOBJ = $(PLINTHOBJ0:>=.obj)
+AMSOBJ = $(AMSOBJ0:>=.obj)
+AMCOBJ = $(AMCOBJ0:>=.obj)
+AWLOBJ = $(AWLOBJ0:>=.obj)
+LOOBJ = $(LOOBJ0:>=.obj)
+SNCOBJ = $(SNCOBJ0:>=.obj)
+MVFFOBJ = $(MVFFOBJ0:>=.obj)
+DWOBJ = $(DWOBJ0:>=.obj)
+FMTTESTOBJ = $(FMTTESTOBJ0:>=.obj)
+POOLNOBJ = $(POOLNOBJ0:>=.obj)
+TESTLIBOBJ = $(TESTLIBOBJ0:>=.obj)
+
+
+!INCLUDE commpost.nmk
+
+
+# C. COPYRIGHT AND LICENSE
+#
+# Copyright (C) 2001-2014 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.
diff --git a/mps/code/zcoll.c b/mps/code/zcoll.c
index 9f8701ca1f5..646d8c7d30a 100644
--- a/mps/code/zcoll.c
+++ b/mps/code/zcoll.c
@@ -196,8 +196,8 @@ static void get(mps_arena_t arena)
     switch(type) {
       case mps_message_type_gc_start(): {
         mclockBegin = mps_message_clock(arena, message);
-        printf("    %5lu: (%5lu)",
-               mclockBegin, mclockBegin - mclockEnd);
+        printf("    %5"PRIuLONGEST": (%5"PRIuLONGEST")",
+               (ulongest_t)mclockBegin, (ulongest_t)(mclockBegin - mclockEnd));
         printf("    Coll Begin                                     (%s)\n",
                mps_message_gc_start_why(arena, message));
         break;
@@ -211,8 +211,8 @@ static void get(mps_arena_t arena)
 
         mclockEnd = mps_message_clock(arena, message);
         
-        printf("    %5lu: (%5lu)",
-               mclockEnd, mclockEnd - mclockBegin);
+        printf("    %5"PRIuLONGEST": (%5"PRIuLONGEST")",
+               (ulongest_t)mclockEnd, (ulongest_t)(mclockEnd - mclockBegin));
         printf("    Coll End  ");
         showStatsText(notcon, con, live);
         if(rnd()==0) showStatsAscii(notcon, con, live, alimit);
@@ -222,7 +222,8 @@ static void get(mps_arena_t arena)
         mps_message_finalization_ref(&objaddr, arena, message);
         obj = objaddr;
         objind = DYLAN_INT_INT(DYLAN_VECTOR_SLOT(obj, 0));
-        printf("    Finalization for object %lu at %p\n", objind, objaddr);
+        printf("    Finalization for object %"PRIuLONGEST" at %p\n",
+               (ulongest_t)objind, objaddr);
         break;
       }
       default: {
@@ -301,7 +302,7 @@ static void CatalogCheck(void)
   mps_word_t w;
   void *Catalog, *Page, *Art, *Poly;
   unsigned long Catalogs = 0, Pages = 0, Arts = 0, Polys = 0;
-  int i, j, k;
+  size_t i, j, k;
 
   /* retrieve Catalog from root */
   Catalog = myrootExact[CatalogRootIndex];
@@ -359,7 +360,7 @@ static void CatalogDo(mps_arena_t arena, mps_ap_t ap)
 {
   mps_word_t v;
   void *Catalog, *Page, *Art, *Poly;
-  int i, j, k;
+  size_t i, j, k;
 
   die(make_dylan_vector(&v, ap, CatalogFix + CatalogVar), "Catalog");
   DYLAN_VECTOR_SLOT(v, 0) = DYLAN_INT(CatalogSig);
@@ -381,7 +382,7 @@ static void CatalogDo(mps_arena_t arena, mps_ap_t ap)
     DYLAN_VECTOR_SLOT(Catalog, CatalogFix + i) = (mps_word_t)Page;
     get(arena);
     
-    printf("Page %d: make articles\n", i);
+    printf("Page %"PRIuLONGEST": make articles\n", (ulongest_t)i);
     (void)fflush(stdout);
     
     for(j = 0; j < PageVar; j += 1) {
@@ -531,7 +532,7 @@ static void Make(mps_arena_t arena, mps_ap_t ap, unsigned randm, unsigned keep1i
 
 static void Rootdrop(char rank_char)
 {
-  unsigned i;
+  size_t i;
   
   if(rank_char == 'A') {
     for(i = 0; i < myrootAmbigCOUNT; ++i) {
@@ -550,7 +551,7 @@ static void Rootdrop(char rank_char)
 #define stackwipedepth 50000
 static void stackwipe(void)
 {
-  unsigned iw;
+  size_t iw;
   unsigned long aw[stackwipedepth];
   
   /* Do some pointless work that the compiler won't optimise away, so that
@@ -734,7 +735,7 @@ static void *testscriptB(void *arg, size_t s)
   mps_fmt_t fmt;
   mps_chain_t chain;
   mps_pool_t amc;
-  int i;
+  size_t i;
   mps_root_t root_table_Ambig;
   mps_root_t root_table_Exact;
   mps_ap_t ap;
diff --git a/mps/code/zmess.c b/mps/code/zmess.c
index e032b3f7620..2b6d533dfde 100644
--- a/mps/code/zmess.c
+++ b/mps/code/zmess.c
@@ -179,7 +179,8 @@ static void report(mps_arena_t arena, const char *pm, Bool discard)
         mps_message_finalization_ref(&objaddr, arena, message);
         obj = objaddr;
         objind = DYLAN_INT_INT(DYLAN_VECTOR_SLOT(obj, 0));
-        printf("    Finalization for object %lu at %p\n", objind, objaddr);
+        printf("    Finalization for object %"PRIuLONGEST" at %p\n",
+               (ulongest_t)objind, objaddr);
         cdie(myroot[objind] == NULL, "finalized live");
         cdie(state[objind] == finalizableSTATE, "not finalizable");
         state[objind] = finalizedSTATE;
@@ -308,7 +309,7 @@ static void *testscriptB(void *arg, size_t s)
   mps_root_t root_table;
   mps_ap_t ap;
   mps_root_t root_stackreg;
-  int i;
+  size_t i;
   int N = myrootCOUNT - 1;
   void *stack_starts_here;  /* stack scanning starts here */