merge 3.3
diff --git a/Lib/test/test_json/test_encode_basestring_ascii.py b/Lib/test/test_json/test_encode_basestring_ascii.py
index a2bbc7d..2122da1 100644
--- a/Lib/test/test_json/test_encode_basestring_ascii.py
+++ b/Lib/test/test_json/test_encode_basestring_ascii.py
@@ -45,6 +45,7 @@
 class TestCEncodeBasestringAscii(TestEncodeBasestringAscii, CTest):
     @bigaddrspacetest
     def test_overflow(self):
-        s = "\uffff"*((2**32)//6 + 1)
+        size = (2**32)//6 + 1
+        s = "\x00"*size
         with self.assertRaises(OverflowError):
             self.json.encoder.encode_basestring_ascii(s)