diff --git a/src/zodbpickle/tests/pickletester.py b/src/zodbpickle/tests/pickletester.py
index 65dbedd..0b3be70 100644
--- a/src/zodbpickle/tests/pickletester.py
+++ b/src/zodbpickle/tests/pickletester.py
@@ -427,7 +427,7 @@ def create_data():
     x.append(5)
     return x
 
-class AbstractPickleTests(unittest.TestCase):
+class AbstractPickleTests:
     # Subclass must define self.dumps, self.loads.
 
     _testdata = create_data()
@@ -1206,7 +1206,7 @@ def test_negative_32b_binput(self):
         self.assertRaises(ValueError, self.loads, dumped)
 
 
-class BigmemPickleTests(unittest.TestCase):
+class BigmemPickleTests:
 
     # Binary protocols can serialize longs of up to 2GB-1
 
@@ -1370,7 +1370,7 @@ def __getattr__(self, key):
         self.foo
 
 
-class AbstractPickleModuleTests(unittest.TestCase):
+class AbstractPickleModuleTests:
 
     def test_dump_closed_file(self):
         import os
@@ -1430,7 +1430,7 @@ def test_bad_input(self):
         self.assertRaises(EOFError, pickle.loads, s)
 
 
-class AbstractPersistentPicklerTests(unittest.TestCase):
+class AbstractPersistentPicklerTests:
 
     # This class defines persistent_id() and persistent_load()
     # functions that should be used by the pickler.  All even integers
@@ -1466,7 +1466,7 @@ def test_bin_persistence(self):
         self.assertEqual(self.load_count, 5)
 
 
-class AbstractPicklerUnpicklerObjectTests(unittest.TestCase):
+class AbstractPicklerUnpicklerObjectTests:
 
     pickler_class = None
     unpickler_class = None
@@ -1629,7 +1629,7 @@ def __reduce__(self):
 class BBB(object):
     pass
 
-class AbstractDispatchTableTests(unittest.TestCase):
+class AbstractDispatchTableTests:
 
     def test_default_dispatch_table(self):
         # No dispatch_table attribute by default
diff --git a/src/zodbpickle/tests/test_pickle.py b/src/zodbpickle/tests/test_pickle.py
index f93688f..77e2732 100644
--- a/src/zodbpickle/tests/test_pickle.py
+++ b/src/zodbpickle/tests/test_pickle.py
@@ -1,6 +1,6 @@
-import pickle
 import io
 import collections
+import unittest
 
 from test import support
 
@@ -11,18 +11,20 @@
 from .pickletester import AbstractDispatchTableTests
 from .pickletester import BigmemPickleTests
 
+from zodbpickle import pickle
+
 try:
-    import _pickle
+    from zodbpickle import _pickle
     has_c_implementation = True
 except ImportError:
     has_c_implementation = False
 
 
-class PickleTests(AbstractPickleModuleTests):
+class PickleTests(AbstractPickleModuleTests, unittest.TestCase):
     pass
 
 
-class PyPicklerTests(AbstractPickleTests):
+class PyPicklerTests(AbstractPickleTests, unittest.TestCase):
 
     pickler = pickle._Pickler
     unpickler = pickle._Unpickler
@@ -40,7 +42,8 @@ def loads(self, buf, **kwds):
         return u.load()
 
 
-class InMemoryPickleTests(AbstractPickleTests, BigmemPickleTests):
+class InMemoryPickleTests(AbstractPickleTests, BigmemPickleTests,
+                          unittest.TestCase):
 
     pickler = pickle._Pickler
     unpickler = pickle._Unpickler
@@ -52,7 +55,7 @@ def loads(self, buf, **kwds):
         return pickle.loads(buf, **kwds)
 
 
-class PyPersPicklerTests(AbstractPersistentPicklerTests):
+class PyPersPicklerTests(AbstractPersistentPicklerTests, unittest.TestCase):
 
     pickler = pickle._Pickler
     unpickler = pickle._Unpickler