diff -r 00348c0518f8 Python/dtoa.c
--- a/Python/dtoa.c	Mon Nov 18 10:04:07 2013 +0100
+++ b/Python/dtoa.c	Mon Nov 18 10:18:53 2013 +0100
@@ -1531,6 +1531,7 @@
 {
     int bb2, bb5, bbe, bd2, bd5, bs2, c, dsign, e, e1, error;
     int esign, i, j, k, lz, nd, nd0, odd, sign;
+    Py_ssize_t tmp;
     const char *s, *s0, *s1;
     double aadj, aadj1;
     U aadj2, adj, rv, rv0;
@@ -1566,7 +1567,8 @@
     s0 = s1 = s;
     while ('0' <= c && c <= '9')
         c = *++s;
-    nd0 = nd = s - s1;
+    tmp = s - s1;
+    nd0 = nd = Py_SAFE_DOWNCAST(tmp, Py_SSIZE_T, int);
 
     /* Parse decimal point and following digits. */
     if (c == '.') {
@@ -1576,13 +1578,15 @@
             while (c == '0')
                 c = *++s;
             lz = lz || s != s1;
-            nd0 -= s - s1;
+            tmp = nd0 - (s - s1);
+            nd0 = Py_SAFE_DOWNCAST(tmp, Py_SSIZE_T, int);
             s0 = s;
         }
         s1 = s;
         while ('0' <= c && c <= '9')
             c = *++s;
-        nd += s - s1;
+        tmp = nd + (s - s1);
+        nd = Py_SAFE_DOWNCAST(tmp, Py_SSIZE_T, int);
     }
 
     /* Now lz is true if and only if there were leading zero digits, and nd