Index: Objects/abstract.c
===================================================================
--- Objects/abstract.c	(revision 66059)
+++ Objects/abstract.c	(working copy)
@@ -3068,7 +3068,11 @@
 {
 	PyObject *result;
 	assert(PyIter_Check(iter));
-	result = (*iter->ob_type->tp_iternext)(iter);
+	if (*iter->ob_type->tp_iternext  != NULL)
+	    result = (*iter->ob_type->tp_iternext)(iter);
+        else {
+    	    return NULL;
+	}
 	if (result == NULL &&
 	    PyErr_Occurred() &&
 	    PyErr_ExceptionMatches(PyExc_StopIteration))
Index: Objects/enumobject.c
===================================================================
--- Objects/enumobject.c	(revision 66059)
+++ Objects/enumobject.c	(working copy)
@@ -127,7 +127,11 @@
 	PyObject *result = en->en_result;
 	PyObject *it = en->en_sit;
 
-	next_item = (*Py_TYPE(it)->tp_iternext)(it);
+	if (*Py_TYPE(it)->tp_iternext != NULL)
+		next_item = (*Py_TYPE(it)->tp_iternext)(it);
+	else {
+		return NULL;
+	}
 	if (next_item == NULL)
 		return NULL;