diff -r 7ed9c601accd Modules/_pickle.c
--- a/Modules/_pickle.c	Fri Feb 06 09:59:05 2015 -0800
+++ b/Modules/_pickle.c	Sun Feb 08 10:55:18 2015 +0200
@@ -1979,7 +1979,7 @@
         if (_Pickler_Write(self, &op, 1) < 0)
             goto done;
 
-        buf = PyOS_double_to_string(x, 'g', 17, 0, NULL);
+        buf = PyOS_double_to_string(x, 'r', 0, Py_DTSF_ADD_DOT_0, NULL);
         if (!buf) {
             PyErr_NoMemory();
             goto done;