=== modified file 'Lib/test/test_bisect.py'
--- Lib/test/test_bisect.py	2008-07-10 14:03:19 +0000
+++ Lib/test/test_bisect.py	2008-09-26 17:00:22 +0000
@@ -196,6 +196,17 @@
     def test_backcompatibility(self):
         self.assertEqual(self.module.insort, self.module.insort_right)
 
+    def test_listDerived(self):
+        class List(list):
+            data = []
+            def insert(self, index, item):
+                self.data.insert(index, item)
+
+        lst = List()
+        self.module.insort_left(lst, 10)
+        self.module.insort_right(lst, 5)
+        self.assertEqual([5, 10], lst.data)
+
 class TestInsortPython(TestInsort):
     module = py_bisect
 

=== modified file 'Modules/_bisectmodule.c'
--- Modules/_bisectmodule.c	2008-07-24 05:38:48 +0000
+++ Modules/_bisectmodule.c	2008-09-26 19:37:13 +0000
@@ -82,7 +82,7 @@
 	index = internal_bisect_right(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {
@@ -183,7 +183,7 @@
 	index = internal_bisect_left(list, item, lo, hi);
 	if (index < 0)
 		return NULL;
-	if (PyList_Check(list)) {
+	if (PyList_CheckExact(list)) {
 		if (PyList_Insert(list, index, item) < 0)
 			return NULL;
 	} else {