diff -r 8befb15024b5 Lib/test/test_random.py
--- a/Lib/test/test_random.py	Fri Jul 10 22:26:44 2015 +0300
+++ b/Lib/test/test_random.py	Sun Jul 12 23:01:38 2015 +0300
@@ -338,6 +338,11 @@ class MersenneTwister_TestBasicOps(TestB
         self.assertRaises(TypeError, self.gen.setstate, (2, ('a',)*625, None))
         # Last element s/b an int also
         self.assertRaises(TypeError, self.gen.setstate, (2, (0,)*624+('a',), None))
+        # Last element s/b between 0 and 624
+        with self.assertRaises((ValueError, OverflowError)):
+            self.gen.setstate((2, (1,)*624+(625,), None))
+        with self.assertRaises((ValueError, OverflowError)):
+            self.gen.setstate((2, (1,)*624+(-1,), None))
 
         # Little trick to make "tuple(x % (2**32) for x in internalstate)"
         # raise ValueError. I cannot think of a simple way to achieve this, so
diff -r 8befb15024b5 Modules/_randommodule.c
--- a/Modules/_randommodule.c	Fri Jul 10 22:26:44 2015 +0300
+++ b/Modules/_randommodule.c	Sun Jul 12 23:01:38 2015 +0300
@@ -335,6 +335,10 @@ random_setstate(RandomObject *self, PyOb
     index = PyLong_AsLong(PyTuple_GET_ITEM(state, i));
     if (index == -1 && PyErr_Occurred())
         return NULL;
+    if (index < 0 || index > N) {
+        PyErr_SetString(PyExc_ValueError, "invalid state");
+        return NULL;
+    }
     self->index = (int)index;
 
     Py_INCREF(Py_None);