diff --git a/Modules/cPickle.c b/Modules/cPickle.c
--- a/Modules/cPickle.c
+++ b/Modules/cPickle.c
@@ -139,15 +139,15 @@
 
 typedef struct {
     PyObject_HEAD
-    int length;         /* number of initial slots in data currently used */
-    int size;           /* number of slots in data allocated */
+    Py_ssize_t length;         /* number of initial slots in data currently used */
+    Py_ssize_t size;           /* number of slots in data allocated */
     PyObject **data;
 } Pdata;
 
 static void
 Pdata_dealloc(Pdata *self)
 {
-    int i;
+    Py_ssize_t i;
     PyObject **p;
 
     for (i = self->length, p = self->data; --i >= 0; p++) {
@@ -193,9 +193,9 @@
  * number of items, this is a (non-erroneous) NOP.
  */
 static int
-Pdata_clear(Pdata *self, int clearto)
+Pdata_clear(Pdata *self, Py_ssize_t clearto)
 {
-    int i;
+    Py_ssize_t i;
     PyObject **p;
 
     if (clearto < 0) return stackUnderflow();
@@ -214,18 +214,17 @@
 static int
 Pdata_grow(Pdata *self)
 {
-    int bigger;
-    size_t nbytes;
+    Py_ssize_t bigger;
+    Py_ssize_t nbytes;
+
     PyObject **tmp;
 
+    if (self->size > (PY_SSIZE_T_MAX >> 1))
+        goto nomemory;
     bigger = self->size << 1;
-    if (bigger <= 0)            /* was 0, or new value overflows */
+    if (bigger > (PY_SSIZE_T_MAX / sizeof(PyObject *)))
         goto nomemory;
-    if ((int)(size_t)bigger != bigger)
-        goto nomemory;
-    nbytes = (size_t)bigger * sizeof(PyObject *);
-    if (nbytes / sizeof(PyObject *) != (size_t)bigger)
-        goto nomemory;
+    nbytes = bigger * sizeof(PyObject *);
     tmp = realloc(self->data, nbytes);
     if (tmp == NULL)
         goto nomemory;
@@ -280,10 +279,10 @@
 
 
 static PyObject *
-Pdata_popTuple(Pdata *self, int start)
+Pdata_popTuple(Pdata *self, Py_ssize_t start)
 {
     PyObject *r;
-    int i, j, l;
+    Py_ssize_t i, j, l;
 
     l = self->length-start;
     r = PyTuple_New(l);
@@ -297,10 +296,10 @@
 }
 
 static PyObject *
-Pdata_popList(Pdata *self, int start)
+Pdata_popList(Pdata *self, Py_ssize_t start)
 {
     PyObject *r;
-    int i, j, l;
+    Py_ssize_t i, j, l;
 
     l=self->length-start;
     if (!( r=PyList_New(l)))  return NULL;
@@ -347,9 +346,9 @@
     int bin;
 
     int fast; /* Fast mode doesn't save in memo, don't use if circ ref */
-    int (*write_func)(struct Picklerobject *, const char *, Py_ssize_t);
+    Py_ssize_t (*write_func)(struct Picklerobject *, const char *, Py_ssize_t);
     char *write_buf;
-    int buf_size;
+    Py_ssize_t buf_size;
     PyObject *dispatch_table;
     int fast_container; /* count nested container dumps */
     PyObject *fast_memo;
@@ -373,12 +372,12 @@
     PyObject *mark;
     PyObject *pers_func;
     PyObject *last_string;
-    int *marks;
-    int num_marks;
-    int marks_size;
+    Py_ssize_t *marks;
+    Py_ssize_t num_marks;
+    Py_ssize_t marks_size;
     Py_ssize_t (*read_func)(struct Unpicklerobject *, char **, Py_ssize_t);
     Py_ssize_t (*readline_func)(struct Unpicklerobject *, char **);
-    int buf_size;
+    Py_ssize_t buf_size;
     char *buf;
     PyObject *find_class;
 } Unpicklerobject;
@@ -424,7 +423,7 @@
     return NULL;
 }
 
-static int
+static Py_ssize_t
 write_file(Picklerobject *self, const char *s, Py_ssize_t  n)
 {
     size_t nbyteswritten;
@@ -433,11 +432,6 @@
         return 0;
     }
 
-    if (n > INT_MAX) {
-        /* String too large */
-        return -1;
-    }
-
     PyFile_IncUseCount((PyFileObject *)self->file);
     Py_BEGIN_ALLOW_THREADS
     nbyteswritten = fwrite(s, sizeof(char), n, self->fp);
@@ -448,10 +442,10 @@
         return -1;
     }
 
-    return (int)n;
+    return n;
 }
 
-static int
+static Py_ssize_t
 write_cStringIO(Picklerobject *self, const char *s, Py_ssize_t  n)
 {
     if (s == NULL) {
@@ -462,26 +456,21 @@
         return -1;
     }
 
-    return (int)n;
+    return n;
 }
 
-static int
+static Py_ssize_t
 write_none(Picklerobject *self, const char *s, Py_ssize_t  n)
 {
     if (s == NULL) return 0;
-    if (n > INT_MAX) return -1;
-    return (int)n;
+    return n;
 }
 
-static int
-write_other(Picklerobject *self, const char *s, Py_ssize_t  _n)
+static Py_ssize_t
+write_other(Picklerobject *self, const char *s, Py_ssize_t  n)
 {
     PyObject *py_str = 0, *junk = 0;
-    int n;
-
-    if (_n > INT_MAX)
-        return -1;
-    n = (int)_n;
+
     if (s == NULL) {
         if (!( self->buf_size ))  return 0;
         py_str = PyString_FromStringAndSize(self->write_buf,
@@ -531,7 +520,7 @@
     size_t nbytesread;
 
     if (self->buf_size == 0) {
-        int size;
+        Py_ssize_t size;
 
         size = ((n < 32) ? 32 : n);
         if (!( self->buf = (char *)malloc(size))) {
@@ -575,7 +564,7 @@
 static Py_ssize_t
 readline_file(Unpicklerobject *self, char **s)
 {
-    int i;
+    Py_ssize_t i;
 
     if (self->buf_size == 0) {
         if (!( self->buf = (char *)malloc(40))) {
@@ -587,7 +576,7 @@
 
     i = 0;
     while (1) {
-        int bigger;
+        Py_ssize_t bigger;
         char *newbuf;
         for (; i < (self->buf_size - 1); i++) {
             if (feof(self->fp) ||
@@ -597,13 +586,13 @@
                 return i + 1;
             }
         }
-        bigger = self->buf_size << 1;
-        if (bigger <= 0) {              /* overflow */
+        if (self->buf_size < (PY_SSIZE_T_MAX >> 1)) {
             PyErr_NoMemory();
             return -1;
         }
+        bigger = self->buf_size << 1;
         newbuf = (char *)realloc(self->buf, bigger);
-        if (!newbuf)  {
+        if (newbuf == NULL)  {
             PyErr_NoMemory();
             return -1;
         }
@@ -700,7 +689,7 @@
  * The caller is responsible for free()'ing the return value.
  */
 static char *
-pystrndup(const char *s, int n)
+pystrndup(const char *s, Py_ssize_t n)
 {
     char *r = (char *)malloc(n+1);
     if (r == NULL)
@@ -715,7 +704,7 @@
 get(Picklerobject *self, PyObject *id)
 {
     PyObject *value, *mv;
-    long c_value;
+    Py_ssize_t c_value;
     char s[30];
     size_t len;
 
@@ -735,7 +724,8 @@
 
     if (!self->bin) {
         s[0] = GET;
-        PyOS_snprintf(s + 1, sizeof(s) - 1, "%ld\n", c_value);
+        PyOS_snprintf(s + 1, sizeof(s) - 1,
+                      "%" PY_FORMAT_SIZE_T "d\n", c_value);
         len = strlen(s);
     }
     else if (Pdata_Check(self->file)) {
@@ -780,8 +770,7 @@
 put2(Picklerobject *self, PyObject *ob)
 {
     char c_str[30];
-    int p;
-    size_t len;
+    Py_ssize_t len, p;
     int res = -1;
     PyObject *py_ob_id = 0, *memo_len = 0, *t = 0;
 
@@ -994,7 +983,7 @@
 {
     char c_str[32];
     long l = PyInt_AS_LONG((PyIntObject *)args);
-    int len = 0;
+    Py_ssize_t len = 0;
 
     if (!self->bin
 #if SIZEOF_LONG > 4
@@ -1201,7 +1190,7 @@
 static int
 save_string(Picklerobject *self, PyObject *args, int doput)
 {
-    int size, len;
+    Py_ssize_t size, len;
     PyObject *repr=0;
 
     if ((size = PyString_Size(args)) < 0)
@@ -1448,7 +1437,7 @@
 static int
 store_tuple_elements(Picklerobject *self, PyObject *t, int len)
 {
-    int i;
+    Py_ssize_t i;
     int res = -1;       /* guilty until proved innocent */
 
     assert(PyTuple_Size(t) == len);
@@ -1477,7 +1466,7 @@
 save_tuple(Picklerobject *self, PyObject *args)
 {
     PyObject *py_tuple_id = NULL;
-    int len, i;
+    Py_ssize_t len, i;
     int res = -1;
 
     static char tuple = TUPLE;
@@ -1690,7 +1679,7 @@
 {
     int res = -1;
     char s[3];
-    int len;
+    Py_ssize_t len;
     PyObject *iter;
 
     if (self->fast && !fast_save_enter(self, args))
@@ -1943,7 +1932,7 @@
 {
     int res = -1;
     char s[3];
-    int len;
+    Py_ssize_t len;
 
     if (self->fast && !fast_save_enter(self, args))
         goto finally;
@@ -2289,7 +2278,8 @@
 save_pers(Picklerobject *self, PyObject *args, PyObject *f)
 {
     PyObject *pid = 0;
-    int size, res = -1;
+    Py_ssize_t size;
+    int res = -1;
 
     static char persid = PERSID, binpersid = BINPERSID;
 
@@ -2815,7 +2805,7 @@
 static PyObject *
 Pickle_getvalue(Picklerobject *self, PyObject *args)
 {
-    int l, i, rsize, ssize, clear=1, lm;
+    Py_ssize_t l, i, rsize, ssize, clear=1, lm;
     long ik;
     PyObject *k, *r;
     char *s, *p, *have_get;
@@ -3314,7 +3304,7 @@
     return global;
 }
 
-static int
+static Py_ssize_t
 marker(Unpicklerobject *self)
 {
     if (self->num_marks < 1) {
@@ -3345,7 +3335,8 @@
 {
     PyObject *py_int = 0;
     char *endptr, *s;
-    int len, res = -1;
+    Py_ssize_t len;
+    int res = -1;
     long l;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
@@ -3477,7 +3468,8 @@
 {
     PyObject *l = 0;
     char *end, *s;
-    int len, res = -1;
+    Py_ssize_t len;
+    int res = -1;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
     if (len < 2) return bad_readline();
@@ -3541,7 +3533,8 @@
 {
     PyObject *py_float = 0;
     char *endptr, *s;
-    int len, res = -1;
+    Py_ssize_t len;
+    int res = -1;
     double d;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
@@ -3597,7 +3590,8 @@
 load_string(Unpicklerobject *self)
 {
     PyObject *str = 0;
-    int len, res = -1;
+    int res = -1;
+    Py_ssize_t len;
     char *s, *p;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
@@ -3639,7 +3633,7 @@
 load_binstring(Unpicklerobject *self)
 {
     PyObject *py_string = 0;
-    long l;
+    Py_ssize_t l;
     char *s;
 
     if (self->read_func(self, &s, 4) < 0) return -1;
@@ -3691,7 +3685,7 @@
 load_unicode(Unpicklerobject *self)
 {
     PyObject *str = 0;
-    int len, res = -1;
+    Py_ssize_t len, res = -1;
     char *s;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
@@ -3714,7 +3708,7 @@
 load_binunicode(Unpicklerobject *self)
 {
     PyObject *unicode;
-    long l;
+    Py_ssize_t l;
     char *s;
 
     if (self->read_func(self, &s, 4) < 0) return -1;
@@ -3745,7 +3739,7 @@
 load_tuple(Unpicklerobject *self)
 {
     PyObject *tup;
-    int i;
+    Py_ssize_t i;
 
     if ((i = marker(self)) < 0) return -1;
     if (!( tup=Pdata_popTuple(self->stack, i)))  return -1;
@@ -3798,7 +3792,7 @@
 load_list(Unpicklerobject *self)
 {
     PyObject *list = 0;
-    int i;
+    Py_ssize_t i;
 
     if ((i = marker(self)) < 0) return -1;
     if (!( list=Pdata_popList(self->stack, i)))  return -1;
@@ -3810,7 +3804,7 @@
 load_dict(Unpicklerobject *self)
 {
     PyObject *dict, *key, *value;
-    int i, j, k;
+    Py_ssize_t i, j, k;
 
     if ((i = marker(self)) < 0) return -1;
     j=self->stack->length;
@@ -3886,7 +3880,7 @@
 load_obj(Unpicklerobject *self)
 {
     PyObject *class, *tup, *obj=0;
-    int i;
+    Py_ssize_t i;
 
     if ((i = marker(self)) < 0) return -1;
     if (!( tup=Pdata_popTuple(self->stack, i+1)))  return -1;
@@ -3907,7 +3901,7 @@
 load_inst(Unpicklerobject *self)
 {
     PyObject *tup, *class=0, *obj=0, *module_name, *class_name;
-    int i, len;
+    Py_ssize_t i, len;
     char *s;
 
     if ((i = marker(self)) < 0) return -1;
@@ -3993,7 +3987,7 @@
 load_global(Unpicklerobject *self)
 {
     PyObject *class = 0, *module_name = 0, *class_name = 0;
-    int len;
+    Py_ssize_t len;
     char *s;
 
     if ((len = self->readline_func(self, &s)) < 0) return -1;
@@ -4024,7 +4018,7 @@
 load_persid(Unpicklerobject *self)
 {
     PyObject *pid = 0;
-    int len;
+    Py_ssize_t len;
     char *s;
 
     if (self->pers_func) {
@@ -4102,7 +4096,7 @@
 static int
 load_pop(Unpicklerobject *self)
 {
-    int len = self->stack->length;
+    Py_ssize_t len = self->stack->length;
 
     /* Note that we split the (pickle.py) stack into two stacks,
        an object stack and a mark stack. We have to be clever and
@@ -4127,7 +4121,7 @@
 static int
 load_pop_mark(Unpicklerobject *self)
 {
-    int i;
+    Py_ssize_t i;
 
     if ((i = marker(self)) < 0)
         return -1;
@@ -4142,7 +4136,7 @@
 load_dup(Unpicklerobject *self)
 {
     PyObject *last;
-    int len;
+    Py_ssize_t len;
 
     if ((len = self->stack->length) <= 0) return stackUnderflow();
     last=self->stack->data[len-1];
@@ -4156,7 +4150,7 @@
 load_get(Unpicklerobject *self)
 {
     PyObject *py_str = 0, *value = 0;
-    int len;
+    Py_ssize_t len;
     char *s;
     int rc;
 
@@ -4214,7 +4208,7 @@
     PyObject *py_key = 0, *value = 0;
     unsigned char c;
     char *s;
-    long key;
+    Py_ssize_t key;
     int rc;
 
     if (self->read_func(self, &s, 4) < 0) return -1;
@@ -4317,7 +4311,7 @@
 load_put(Unpicklerobject *self)
 {
     PyObject *py_str = 0, *value = 0;
-    int len, l;
+    Py_ssize_t len, l;
     char *s;
 
     if ((l = self->readline_func(self, &s)) < 0) return -1;
@@ -4337,7 +4331,7 @@
     PyObject *py_key = 0, *value = 0;
     unsigned char key;
     char *s;
-    int len;
+    Py_ssize_t len;
 
     if (self->read_func(self, &s, 1) < 0) return -1;
     if (!( (len=self->stack->length) > 0 ))  return stackUnderflow();
@@ -4356,10 +4350,10 @@
 load_long_binput(Unpicklerobject *self)
 {
     PyObject *py_key = 0, *value = 0;
-    long key;
+    Py_ssize_t key;
     unsigned char c;
     char *s;
-    int len;
+    Py_ssize_t len;
 
     if (self->read_func(self, &s, 4) < 0) return -1;
     if (!( len=self->stack->length ))  return stackUnderflow();
@@ -4382,10 +4376,10 @@
 
 
 static int
-do_append(Unpicklerobject *self, int  x)
+do_append(Unpicklerobject *self, Py_ssize_t  x)
 {
     PyObject *value = 0, *list = 0, *append_method = 0;
-    int len, i;
+    Py_ssize_t len, i;
 
     len=self->stack->length;
     if (!( len >= x && x > 0 ))  return stackUnderflow();
@@ -4451,11 +4445,11 @@
 }
 
 
-static int
-do_setitems(Unpicklerobject *self, int  x)
+static Py_ssize_t
+do_setitems(Unpicklerobject *self, Py_ssize_t x)
 {
     PyObject *value = 0, *key = 0, *dict = 0;
-    int len, i, r=0;
+    Py_ssize_t len, i, r=0;
 
     if (!( (len=self->stack->length) >= x
            && x > 0 ))  return stackUnderflow();
@@ -4496,8 +4490,8 @@
     PyObject *state, *inst, *slotstate;
     PyObject *__setstate__;
     PyObject *d_key, *d_value;
+    int res = -1;
     Py_ssize_t i;
-    int res = -1;
 
     /* Stack is ... instance, state.  We want to leave instance at
      * the stack top, possibly mutated via instance.__setstate__(state).
@@ -4596,7 +4590,7 @@
 static int
 load_mark(Unpicklerobject *self)
 {
-    int s;
+    Py_ssize_t s;
 
     /* Note that we split the (pickle.py) stack into two stacks, an
        object stack and a mark stack. Here we push a mark onto the
@@ -4981,7 +4975,7 @@
 static int
 noload_obj(Unpicklerobject *self)
 {
-    int i;
+    Py_ssize_t i;
 
     if ((i = marker(self)) < 0) return -1;
     return Pdata_clear(self->stack, i+1);
@@ -4991,7 +4985,7 @@
 static int
 noload_inst(Unpicklerobject *self)
 {
-    int i;
+    Py_ssize_t i;
     char *s;
 
     if ((i = marker(self)) < 0) return -1;
@@ -5068,7 +5062,7 @@
 static int
 noload_appends(Unpicklerobject *self)
 {
-    int i;
+    Py_ssize_t i;
     if ((i = marker(self)) < 0) return -1;
     return Pdata_clear(self->stack, i);
 }
@@ -5082,7 +5076,7 @@
 static int
 noload_setitems(Unpicklerobject *self)
 {
-    int i;
+    Py_ssize_t i;
     if ((i = marker(self)) < 0) return -1;
     return Pdata_clear(self->stack, i);
 }