diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index fdf2b9e8c21..751d1f6a8b7 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -8,14 +8,20 @@
 
 import hashlib
 import StringIO
+import sys
 try:
     import threading
 except ImportError:
     threading = None
 import unittest
+import warnings
 from test import test_support
 from test.test_support import _4G, precisionbigmemtest
 
+# Were we compiled --with-pydebug or with #define Py_DEBUG?
+COMPILED_WITH_PYDEBUG = hasattr(sys, 'gettotalrefcount')
+
+
 def hexstr(s):
     import string
     h = string.hexdigits
@@ -31,6 +37,63 @@ class HashLibTestCase(unittest.TestCase):
                              'sha224', 'SHA224', 'sha256', 'SHA256',
                              'sha384', 'SHA384', 'sha512', 'SHA512' )
 
+    _warn_on_extension_import = COMPILED_WITH_PYDEBUG
+
+    def _conditional_import_module(self, module_name):
+        """Import a module and return a reference to it or None on failure."""
+        try:
+            exec('import '+module_name)
+        except ImportError, error:
+            if self._warn_on_extension_import:
+                warnings.warn('Did a C extension fail to compile? %s' % error)
+        return locals().get(module_name)
+
+    def __init__(self, *args, **kwargs):
+        algorithms = set()
+        for algorithm in self.supported_hash_names:
+            algorithms.add(algorithm.lower())
+        self.constructors_to_test = {}
+        for algorithm in algorithms:
+            self.constructors_to_test[algorithm] = set()
+
+        # For each algorithm, test the direct constructor and the use
+        # of hashlib.new given the algorithm name.
+        for algorithm, constructors in self.constructors_to_test.items():
+            constructors.add(getattr(hashlib, algorithm))
+            def _test_algorithm_via_hashlib_new(data=None, _alg=algorithm):
+                if data is None:
+                    return hashlib.new(_alg)
+                return hashlib.new(_alg, data)
+            constructors.add(_test_algorithm_via_hashlib_new)
+
+        _hashlib = self._conditional_import_module('_hashlib')
+        if _hashlib:
+            # These two algorithms should always be present when this module
+            # is compiled.  If not, something was compiled wrong.
+            assert hasattr(_hashlib, 'openssl_md5')
+            assert hasattr(_hashlib, 'openssl_sha1')
+            for algorithm, constructors in self.constructors_to_test.items():
+                constructor = getattr(_hashlib, 'openssl_'+algorithm, None)
+                if constructor:
+                    constructors.add(constructor)
+
+        _md5 = self._conditional_import_module('_md5')
+        if _md5:
+            self.constructors_to_test['md5'].add(_md5.new)
+        _sha = self._conditional_import_module('_sha')
+        if _sha:
+            self.constructors_to_test['sha1'].add(_sha.new)
+        _sha256 = self._conditional_import_module('_sha256')
+        if _sha256:
+            self.constructors_to_test['sha224'].add(_sha256.sha224)
+            self.constructors_to_test['sha256'].add(_sha256.sha256)
+        _sha512 = self._conditional_import_module('_sha512')
+        if _sha512:
+            self.constructors_to_test['sha384'].add(_sha512.sha384)
+            self.constructors_to_test['sha512'].add(_sha512.sha512)
+
+        super(HashLibTestCase, self).__init__(*args, **kwargs)
+
     def test_unknown_hash(self):
         try:
             hashlib.new('spam spam spam spam spam')
@@ -64,20 +127,22 @@ class HashLibTestCase(unittest.TestCase):
             self.assertEqual(m1.digest(), m3.digest(), name+' new problem.')
 
     def check(self, name, data, digest):
-        # test the direct constructors
-        computed = getattr(hashlib, name)(data).hexdigest()
-        self.assertEqual(computed, digest)
-        # test the general new() interface
-        computed = hashlib.new(name, data).hexdigest()
-        self.assertEqual(computed, digest)
+        constructors = self.constructors_to_test[name]
+        # 2 is for hashlib.name(...) and hashlib.new(name, ...)
+        self.assertGreaterEqual(len(constructors), 2)
+        for hash_object_constructor in constructors:
+            computed = hash_object_constructor(data).hexdigest()
+            self.assertEqual(
+                    computed, digest,
+                    "Hash algorithm %s constructed using %s returned hexdigest"
+                    " %r for %d byte input data that should have hashed to %r."
+                    % (name, hash_object_constructor,
+                       computed, len(data), digest))
 
     def check_unicode(self, algorithm_name):
         # Unicode objects are not allowed as input.
         expected = hashlib.new(algorithm_name, str(u'spam')).hexdigest()
-        self.assertEqual(getattr(hashlib, algorithm_name)(u'spam').hexdigest(),
-                        expected)
-        self.assertEqual(hashlib.new(algorithm_name, u'spam').hexdigest(),
-                         expected)
+        self.check(algorithm_name, u'spam', expected)
 
     def test_unicode(self):
         # In python 2.x unicode is auto-encoded to the system default encoding