diff --git a/gmp-h.in b/gmp-h.in
index 58fc571f..cab0a3b9 100644
--- a/gmp-h.in
+++ b/gmp-h.in
@@ -224,6 +224,10 @@ typedef __gmp_const mp_limb_t *	mp_srcptr;
 #define __GMP_MP_SIZE_T_INT     1
 typedef int			mp_size_t;
 typedef int			mp_exp_t;
+#elif defined( _MSC_VER )
+#define __GMP_MP_SIZE_T_INT     2
+typedef intptr_t		mp_size_t;
+typedef intptr_t		mp_exp_t;
 #else
 #define __GMP_MP_SIZE_T_INT     0
 typedef long int		mp_size_t;
diff --git a/gmp-impl.h b/gmp-impl.h
index ffbc0390..592297b0 100644
--- a/gmp-impl.h
+++ b/gmp-impl.h
@@ -51,7 +51,7 @@ MA 02110-1301, USA. */
    reference, int can be 46 or 64 bits, whereas uint is always 64 bits; and
    short can be 24, 32, 46 or 64 bits, and different for ushort.  */
 
-#if defined _CRAY
+#if defined _CRAY || defined _MSC_VER
 #include <limits.h>
 #endif
 
@@ -551,7 +551,15 @@ void  __gmp_tmp_debug_free  _PROTO ((const char *, int, int,
 #define SHRT_MAX           ((short) (-(SHRT_MIN+1)))
 #endif
 
-#if __GMP_MP_SIZE_T_INT
+#if __GMP_MP_SIZE_T_INT == 2
+#  ifdef  _WIN64 
+#    define MP_SIZE_T_MAX      _I64_MAX
+#    define MP_SIZE_T_MIN      _I64_MIN
+#  else
+#    define MP_SIZE_T_MAX      LONG_MAX
+#    define MP_SIZE_T_MIN      LONG_MIN
+#  endif
+#elif __GMP_MP_SIZE_T_INT
 #define MP_SIZE_T_MAX      INT_MAX
 #define MP_SIZE_T_MIN      INT_MIN
 #else
diff --git a/memory.c b/memory.c
index d91de689..7be3ce71 100644
--- a/memory.c
+++ b/memory.c
@@ -46,7 +46,11 @@ __gmp_default_allocate (size_t size)
   ret = malloc (size);
   if (ret == 0)
     {
+#if defined _MSC_VER && defined _WIN64
+      fprintf (stderr, "GNU MP: Cannot allocate memory (size=%llu)\n", size);
+#else
       fprintf (stderr, "GNU MP: Cannot allocate memory (size=%u)\n", size);
+#endif
       abort ();
     }
 
@@ -94,7 +98,11 @@ __gmp_default_reallocate (void *oldptr, size_t old_size, size_t new_size)
   ret = realloc (oldptr, new_size);
   if (ret == 0)
     {
-      fprintf (stderr, "GNU MP: Cannot reallocate memory (old_size=%u new_size=%u)\n", old_size, new_size);
+#if defined _MSC_VER && defined _WIN64
+        fprintf (stderr, "GNU MP: Cannot reallocate memory (old_size=%llu new_size=%llu)\n", old_size, new_size);
+#else
+        fprintf (stderr, "GNU MP: Cannot reallocate memory (old_size=%u new_size=%u)\n", old_size, new_size);
+#endif
       abort ();
     }
 
diff --git a/mpz/inp_raw.c b/mpz/inp_raw.c
index c82b0b83..cf8e0232 100644
--- a/mpz/inp_raw.c
+++ b/mpz/inp_raw.c
@@ -79,7 +79,7 @@ mpz_inp_raw (mpz_ptr x, FILE *fp)
      Could write "csize -= ((csize & 0x80000000L) << 1)", but that tickles a
      bug in gcc 3.0 for powerpc64 on AIX.  */
   if (sizeof (csize) > 4 && csize & 0x80000000L)
-    csize -= 0x80000000L << 1;
+    csize |= (mp_size_t)(-1) << 32;
 
   abs_csize = ABS (csize);