From 6ef2b36afa5bf694e343f7227c7fa17fc231121a Mon Sep 17 00:00:00 2001
From: Benjamin Peterson <benjamin@python.org>
Date: Mon, 14 Apr 2014 11:45:21 -0400
Subject: [PATCH] disallow a negative idx parameter

---
 Modules/_json.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/Modules/_json.c b/Modules/_json.c
index 5bd52cb7898..4d0f3c473af 100644
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -930,10 +930,11 @@ scan_once_unicode(PyScannerObject *s, PyObject *pystr, Py_ssize_t idx, Py_ssize_
     PyObject *res;
     Py_UNICODE *str = PyUnicode_AS_UNICODE(pystr);
     Py_ssize_t length = PyUnicode_GET_SIZE(pystr);
-    if (idx < 0)
-        /* Compatibility with Python version. */
-        idx += length;
-    if (idx < 0 || idx >= length) {
+    if (idx < 0) {
+        PyErr_SetString(PyExc_ValueError, "idx canont be negative");
+        return NULL;
+    }
+    if (idx >= length) {
         PyErr_SetNone(PyExc_StopIteration);
         return NULL;
     }