diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index e7ce198..4ba07b1 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -2,11 +2,16 @@
 #
 # $Id$
 #
-#  Copyright (C) 2005   Gregory P. Smith (greg@krypto.org)
+#  Copyright (C) 2005-2009   Gregory P. Smith (greg@krypto.org)
 #  Licensed to PSF under a Contributor Agreement.
 #
 
 import hashlib
+import StringIO
+try:
+    import threading
+except ImportError:
+    threading = None
 import unittest
 from test import test_support
 from test.test_support import _4G, precisionbigmemtest
@@ -61,10 +66,10 @@
     def check(self, name, data, digest):
         # test the direct constructors
         computed = getattr(hashlib, name)(data).hexdigest()
-        self.assert_(computed == digest)
+        self.assertEqual(computed, digest)
         # test the general new() interface
         computed = hashlib.new(name, data).hexdigest()
-        self.assert_(computed == digest)
+        self.assertEqual(computed, digest)
 
     def check_no_unicode(self, algorithm_name):
         # Unicode objects are not allowed as input.
@@ -211,6 +216,44 @@
           "e718483d0ce769644e2e42c7bc15b4638e1f98b13b2044285632a803afa973eb"+
           "de0ff244877ea60a4cb0432ce577c31beb009c5c2c49aa2e4eadb217ad8cc09b")
 
+    def test_threaded_hashing(self):
+        if not threading:
+            raise unittest.SkipTest('No threading module.')
+
+        # Updating the same hash object from several threads at once
+        # using data chunk sizes containing the same byte sequences.
+        #
+        # If the internal locks are working to prevent multiple
+        # updates on the same object from running at once, the resulting
+        # hash will be the same as doing it single threaded upfront.
+        hasher = hashlib.sha1()
+        num_threads = 5
+        smallest_data = 'swineflu'
+        data = smallest_data*200000
+        expected_hash = hashlib.sha1(data*num_threads).hexdigest()
+
+        def hash_in_chunks(chunk_size, event):
+            index = 0
+            while index < len(data):
+                hasher.update(data[index:index+chunk_size])
+                index += chunk_size
+            event.set()
+
+        events = []
+        for threadnum in xrange(num_threads):
+            chunk_size = len(data) // (10**threadnum)
+            assert chunk_size > 0
+            assert chunk_size % len(smallest_data) == 0
+            event = threading.Event()
+            events.append(event)
+            threading.Thread(target=hash_in_chunks,
+                             args=(chunk_size, event)).start()
+
+        for event in events:
+            event.wait()
+
+        self.assertEqual(expected_hash, hasher.hexdigest())
+
 
 def test_main():
     test_support.run_unittest(HashLibTestCase)