diff -r 4c7feafa28c3 rpython/translator/c/src/linuxmemchk.c
--- a/rpython/translator/c/src/linuxmemchk.c	Wed Apr 10 07:50:25 2013 -0700
+++ b/rpython/translator/c/src/linuxmemchk.c	Wed Apr 10 11:04:21 2013 -0700
@@ -30,12 +30,12 @@
 static struct _alloc_s* _na_find(void* data)
 {
   int err;
-  long data1;
+  ptrdiff_t data1;
   struct _alloc_s* s;
   _na_assert(_na_start+PAGESIZE <= data &&
              data < _na_start+MALLOC_BIGBUFFER-PAGESIZE,
              "corrupted na_start");
-  data1 = (long) data;
+  data1 = (ptrdiff_t) data;
   data1 &= ~(PAGESIZE-1);
   data1 -= PAGESIZE;
   err = mprotect((void*) data1, PAGESIZE, PROT_READ|PROT_WRITE);
diff -r 4c7feafa28c3 rpython/translator/c/src/obmalloc.c
--- a/rpython/translator/c/src/obmalloc.c	Wed Apr 10 07:50:25 2013 -0700
+++ b/rpython/translator/c/src/obmalloc.c	Wed Apr 10 11:04:21 2013 -0700
@@ -442,7 +442,7 @@
 	arenabase = bp;
 	nfreepools = ARENA_SIZE / POOL_SIZE;
 	assert(POOL_SIZE * nfreepools == ARENA_SIZE);
-	excess = (uint) ((long)bp & POOL_SIZE_MASK);
+	excess = (uint) ((ptrdiff_t)bp & POOL_SIZE_MASK);
 	if (excess != 0) {
 		--nfreepools;
 		arenabase += POOL_SIZE - excess;
diff -r 4c7feafa28c3 rpython/translator/c/src/stack.c
--- a/rpython/translator/c/src/stack.c	Wed Apr 10 07:50:25 2013 -0700
+++ b/rpython/translator/c/src/stack.c	Wed Apr 10 11:04:21 2013 -0700
@@ -7,18 +7,18 @@
 /* the current stack is in the interval [end-length:end].  We assume a
    stack that grows downward here. */
 char *_LLstacktoobig_stack_end = NULL;
-long _LLstacktoobig_stack_length = MAX_STACK_SIZE;
+ptrdiff_t _LLstacktoobig_stack_length = MAX_STACK_SIZE;
 char _LLstacktoobig_report_error = 1;
 static RPyThreadStaticTLS end_tls_key;
 
 void LL_stack_set_length_fraction(double fraction)
 {
-	_LLstacktoobig_stack_length = (long)(MAX_STACK_SIZE * fraction);
+	_LLstacktoobig_stack_length = (ptrdiff_t)(MAX_STACK_SIZE * fraction);
 }
 
-char LL_stack_too_big_slowpath(long current)
+char LL_stack_too_big_slowpath(ptrdiff_t current)
 {
-	long diff, max_stack_size;
+	ptrdiff_t diff, max_stack_size;
 	char *baseptr, *curptr = (char*)current;
 
 	/* The stack_end variable is updated to match the current value
@@ -47,12 +47,12 @@
 	}
 	else {
 		diff = baseptr - curptr;
-		if (((unsigned long)diff) <= (unsigned long)max_stack_size) {
+		if (diff <= max_stack_size) {
 			/* within bounds, probably just had a thread switch */
 			_LLstacktoobig_stack_end = baseptr;
 			return 0;
 		}
-		if (((unsigned long)-diff) <= (unsigned long)max_stack_size) {
+		if (-diff <= max_stack_size) {
 			/* stack underflowed: the initial estimation of
 			   the stack base must be revised */
 		}
diff -r 4c7feafa28c3 rpython/translator/c/src/stacklet/stacklet.c
--- a/rpython/translator/c/src/stacklet/stacklet.c	Wed Apr 10 07:50:25 2013 -0700
+++ b/rpython/translator/c/src/stacklet/stacklet.c	Wed Apr 10 11:04:21 2013 -0700
@@ -331,22 +331,22 @@
 char **_stacklet_translate_pointer(stacklet_handle context, char **ptr)
 {
   char *p = (char *)ptr;
-  long delta;
+  ptrdiff_t delta;
   if (context == NULL)
     return ptr;
   delta = p - context->stack_start;
-  if (((unsigned long)delta) < ((unsigned long)context->stack_saved)) {
+  if (delta < ((ptrdiff_t)context->stack_saved)) {
       /* a pointer to a saved away word */
       char *c = (char *)(context + 1);
       return (char **)(c + delta);
   }
-  if (((unsigned long)delta) >=
-      (unsigned long)(context->stack_stop - context->stack_start)) {
+  if delta >=
+      (ptrdiff_t)(context->stack_stop - context->stack_start)) {
       /* out-of-stack pointer!  it's only ok if we are the main stacklet
          and we are reading past the end, because the main stacklet's
          stack stop is not exactly known. */
       assert(delta >= 0);
-      assert(((long)context->stack_stop) & 1);
+      assert(((ptrdiff_t)context->stack_stop) & 1);
   }
   return ptr;
 }
diff -r 4c7feafa28c3 rpython/translator/c/src/thread_nt.c
--- a/rpython/translator/c/src/thread_nt.c	Wed Apr 10 07:50:25 2013 -0700
+++ b/rpython/translator/c/src/thread_nt.c	Wed Apr 10 11:04:21 2013 -0700
@@ -48,7 +48,7 @@
 
 long RPyThreadStart(void (*func)(void))
 {
-	unsigned long rv;
+	ptrdiff_t rv;
 	callobj obj;
 
 	obj.id = -1;	/* guilty until proved innocent */
@@ -58,7 +58,7 @@
 		return -1;
 
 	rv = _beginthread(bootstrap, _pypythread_stacksize, &obj);
-	if (rv == (unsigned long)-1) {
+	if (rv == (ptrdiff_t)-1) {
 		/* I've seen errno == EAGAIN here, which means "there are
 		 * too many threads".
 		 */
@@ -84,7 +84,7 @@
 	return _pypythread_stacksize;
 }
 
-long RPyThreadSetStackSize(long newsize)
+long RPyThreadSetStackSize(ptrdiff_t newsize)
 {
 	if (newsize == 0) {    /* set to default */
 		_pypythread_stacksize = 0;