diff -r 60430bdcb426 Lib/test/list_tests.py
--- a/Lib/test/list_tests.py	Tue Mar 08 01:11:14 2016 -0500
+++ b/Lib/test/list_tests.py	Tue Mar 08 11:38:22 2016 +0200
@@ -593,3 +593,14 @@ class CommonTest(seq_tests.CommonTest):
             def __iter__(self):
                 raise KeyboardInterrupt
         self.assertRaises(KeyboardInterrupt, list, F())
+
+    def test_exhausted_iterator(self):
+        a = self.type2test([1, 2, 3])
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.append(9)
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [9])
+        self.assertEqual(a, self.type2test([1, 2, 3, 9]))
diff -r 60430bdcb426 Lib/test/test_array.py
--- a/Lib/test/test_array.py	Tue Mar 08 01:11:14 2016 -0500
+++ b/Lib/test/test_array.py	Tue Mar 08 11:38:22 2016 +0200
@@ -318,8 +318,19 @@ class BaseTest:
             d = pickle.dumps((itorig, orig), proto)
             it, a = pickle.loads(d)
             a.fromlist(data2)
-            self.assertEqual(type(it), type(itorig))
-            self.assertEqual(list(it), data2)
+            self.assertEqual(list(it), [])
+
+    def test_exhausted_iterator(self):
+        a = array.array(self.typecode, self.example)
+        self.assertEqual(list(a), list(self.example))
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.append(self.outside)
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [self.outside])
+        self.assertEqual(list(a), list(self.example) + [self.outside])
 
     def test_insert(self):
         a = array.array(self.typecode, self.example)
diff -r 60430bdcb426 Lib/test/test_bytes.py
--- a/Lib/test/test_bytes.py	Tue Mar 08 01:11:14 2016 -0500
+++ b/Lib/test/test_bytes.py	Tue Mar 08 11:38:22 2016 +0200
@@ -17,6 +17,7 @@ import unittest
 import test.support
 import test.string_tests
 import test.buffer_tests
+import test.list_tests
 from test.support import bigaddrspacetest, MAX_Py_ssize_t
 
 
@@ -1414,6 +1415,7 @@ class ByteArrayTest(BaseBytesTest, unitt
             b[:] = data
             self.assertEqual(list(it), [])
 
+    test_exhausted_iterator = test.list_tests.CommonTest.test_exhausted_iterator
 
 class AssortedBytesTest(unittest.TestCase):
     #
diff -r 60430bdcb426 Lib/test/test_iter.py
--- a/Lib/test/test_iter.py	Tue Mar 08 01:11:14 2016 -0500
+++ b/Lib/test/test_iter.py	Tue Mar 08 11:38:22 2016 +0200
@@ -189,6 +189,17 @@ class TestCase(unittest.TestCase):
             self.assertTrue(isinstance(it, collections.abc.Iterator))
             self.assertEqual(list(it), [])
 
+    def test_mutating_seq_class_exhausted_iter(self):
+        a = SequenceClass(5)
+        exhit = iter(a)
+        empit = iter(a)
+        for x in exhit:  # exhaust the iterator
+            next(empit)  # not exhausted
+        a.n = 7
+        self.assertEqual(list(exhit), [])
+        self.assertEqual(list(empit), [5, 6])
+        self.assertEqual(list(a), [0, 1, 2, 3, 4, 5, 6])
+
     # Test a new_style class with __iter__ but no next() method
     def test_new_style_iter_class(self):
         class IterClass(object):
diff -r 60430bdcb426 Modules/arraymodule.c
--- a/Modules/arraymodule.c	Tue Mar 08 01:11:14 2016 -0500
+++ b/Modules/arraymodule.c	Tue Mar 08 11:38:22 2016 +0200
@@ -2875,9 +2875,19 @@ array_iter(arrayobject *ao)
 static PyObject *
 arrayiter_next(arrayiterobject *it)
 {
+    arrayobject *ao;
+
+    assert(it != NULL);
     assert(PyArrayIter_Check(it));
-    if (it->index < Py_SIZE(it->ao))
-        return (*it->getitem)(it->ao, it->index++);
+    ao = it->ao;
+    if (ao == NULL) {
+        return NULL;
+    }
+    assert(array_Check(ao));
+    if (it->index < Py_SIZE(ao))
+        return (*it->getitem)(ao, it->index++);
+    it->ao = NULL;
+    Py_DECREF(ao);
     return NULL;
 }
 
@@ -2906,8 +2916,11 @@ static PyObject *
 array_arrayiterator___reduce___impl(arrayiterobject *self)
 /*[clinic end generated code: output=7898a52e8e66e016 input=a062ea1e9951417a]*/
 {
-    return Py_BuildValue("N(O)n", _PyObject_GetBuiltin("iter"),
-                         self->ao, self->index);
+    PyObject *func = _PyObject_GetBuiltin("iter");
+    if (self->ao == NULL) {
+        return Py_BuildValue("N(())", func);
+    }
+    return Py_BuildValue("N(O)n", func, self->ao, self->index);
 }
 
 /*[clinic input]