diff --git a/third_party/python/Lib/test/test_bisect.py b/third_party/python/Lib/test/test_bisect.py
index 580a963f6..ed8f9eaf8 100644
--- a/third_party/python/Lib/test/test_bisect.py
+++ b/third_party/python/Lib/test/test_bisect.py
@@ -199,6 +199,7 @@ class TestBisect:
         self.module.insort(a=data, x=25, lo=1, hi=3)
         self.assertEqual(data, [10, 20, 25, 25, 25, 30, 40, 50])
 
+@unittest.skipIf(c_bisect, "skip pure-python test if C impl is present")
 class TestBisectPython(TestBisect, unittest.TestCase):
     module = py_bisect
 
@@ -234,6 +235,7 @@ class TestInsort:
         self.module.insort_right(lst, 5)
         self.assertEqual([5, 10], lst.data)
 
+@unittest.skipIf(c_bisect, "skip pure-python test if C impl is present")
 class TestInsortPython(TestInsort, unittest.TestCase):
     module = py_bisect
 
@@ -289,6 +291,7 @@ class TestErrorHandling:
                   self.module.insort_left, self.module.insort_right):
             self.assertRaises(TypeError, f, 10)
 
+@unittest.skipIf(c_bisect, "skip pure-python test if C impl is present")
 class TestErrorHandlingPython(TestErrorHandling, unittest.TestCase):
     module = py_bisect
 
@@ -316,6 +319,7 @@ class TestDocExample:
         self.assertEqual(data[bisect_left(keys, 5)], ('red', 5))
         self.assertEqual(data[bisect_left(keys, 8)], ('yellow', 8))
 
+@unittest.skipIf(c_bisect, "skip pure-python test if C impl is present")
 class TestDocExamplePython(TestDocExample, unittest.TestCase):
     module = py_bisect
 
diff --git a/third_party/python/Lib/test/test_functools.py b/third_party/python/Lib/test/test_functools.py
index 3e3627402..628fdd438 100644
--- a/third_party/python/Lib/test/test_functools.py
+++ b/third_party/python/Lib/test/test_functools.py
@@ -431,7 +431,7 @@ class TestPartialC(TestPartial, unittest.TestCase):
         self.assertIn('astr', r)
         self.assertIn("['sth']", r)
 
-
+@unittest.skipIf(c_functools, "skip pure-python test if C impl is present")
 class TestPartialPy(TestPartial, unittest.TestCase):
     partial = py_functools.partial
 
@@ -458,6 +458,7 @@ class TestPartialCSubclass(TestPartialC):
     # partial subclasses are not optimized for nested calls
     test_nested_optimization = None
 
+@unittest.skipIf(c_functools, "skip pure-python test if C impl is present")
 class TestPartialPySubclass(TestPartialPy):
     partial = PyPartialSubclass
 
@@ -928,6 +929,7 @@ class TestCmpToKeyC(TestCmpToKey, unittest.TestCase):
         cmp_to_key = c_functools.cmp_to_key
 
 
+@unittest.skipIf(c_functools, "skip pure-python test if C impl is present")
 class TestCmpToKeyPy(TestCmpToKey, unittest.TestCase):
     cmp_to_key = staticmethod(py_functools.cmp_to_key)
 
@@ -1565,6 +1567,7 @@ def c_cached_func(x, y):
     return 3 * x + y
 
 
+@unittest.skipIf(c_functools, "skip pure-python test if C impl is present")
 class TestLRUPy(TestLRU, unittest.TestCase):
     module = py_functools
     cached_func = py_cached_func,
diff --git a/third_party/python/Lib/test/test_json/__init__.py b/third_party/python/Lib/test/test_json/__init__.py
index bac370dad..e5aadb1e7 100644
--- a/third_party/python/Lib/test/test_json/__init__.py
+++ b/third_party/python/Lib/test/test_json/__init__.py
@@ -12,6 +12,7 @@ pyjson = support.import_fresh_module('json', blocked=['_json'])
 cjson.JSONDecodeError = cjson.decoder.JSONDecodeError = json.JSONDecodeError
 
 # create two base classes that will be used by the other tests
+@unittest.skipIf(cjson, '_json is available, no need for pure-python tests')
 class PyTest(unittest.TestCase):
     json = pyjson
     loads = staticmethod(pyjson.loads)
diff --git a/third_party/python/Lib/test/test_json/test_recursion.py b/third_party/python/Lib/test/test_json/test_recursion.py
index 03b851013..7e3cb7def 100644
--- a/third_party/python/Lib/test/test_json/test_recursion.py
+++ b/third_party/python/Lib/test/test_json/test_recursion.py
@@ -70,11 +70,11 @@ class TestRecursion:
     def test_highly_nested_objects_decoding(self):
         # test that loading highly-nested objects doesn't segfault when C
         # accelerations are used. See #12017
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             self.loads('{"a":' * 100000 + '1' + '}' * 100000)
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             self.loads('{"a":' * 100000 + '[1]' + '}' * 100000)
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             self.loads('[' * 100000 + '1' + ']' * 100000)
 
     def test_highly_nested_objects_encoding(self):
@@ -82,9 +82,9 @@ class TestRecursion:
         l, d = [], {}
         for x in range(100000):
             l, d = [l], {'k':d}
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             self.dumps(l)
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             self.dumps(d)
 
     def test_endless_recursion(self):
@@ -94,7 +94,7 @@ class TestRecursion:
                 """If check_circular is False, this will keep adding another list."""
                 return [o]
 
-        with self.assertRaises(RecursionError):
+        with self.assertRaises((RecursionError, MemoryError)):
             EndlessJSONEncoder(check_circular=False).encode(5j)
 
 
diff --git a/third_party/python/Lib/test/test_json/test_tool.py b/third_party/python/Lib/test/test_json/test_tool.py
index 9d93f931c..1045a40d5 100644
--- a/third_party/python/Lib/test/test_json/test_tool.py
+++ b/third_party/python/Lib/test/test_json/test_tool.py
@@ -6,6 +6,8 @@ from subprocess import Popen, PIPE
 from test import support
 from test.support.script_helper import assert_python_ok
 
+if __name__ == "PYOBJ.COM":
+    import json.tool
 
 class TestTool(unittest.TestCase):
     data = """
diff --git a/third_party/python/Lib/test/test_operator.py b/third_party/python/Lib/test/test_operator.py
index 6254091e7..3f3625299 100644
--- a/third_party/python/Lib/test/test_operator.py
+++ b/third_party/python/Lib/test/test_operator.py
@@ -496,6 +496,7 @@ class OperatorTestCase:
             if dunder:
                 self.assertIs(dunder, orig)
 
+@unittest.skipIf(c_operator, "skip pure-python test if C impl is present")
 class PyOperatorTestCase(OperatorTestCase, unittest.TestCase):
     module = py_operator
 
diff --git a/third_party/python/Lib/test/test_ordered_dict.py b/third_party/python/Lib/test/test_ordered_dict.py
index b1d7f86a6..3890f010b 100644
--- a/third_party/python/Lib/test/test_ordered_dict.py
+++ b/third_party/python/Lib/test/test_ordered_dict.py
@@ -651,6 +651,7 @@ class OrderedDictTests:
         support.check_free_after_iterating(self, lambda d: iter(d.items()), self.OrderedDict)
 
 
+@unittest.skipIf(c_coll, "skip pure-python test if C impl is present")
 class PurePythonOrderedDictTests(OrderedDictTests, unittest.TestCase):
 
     module = py_coll
@@ -750,6 +751,7 @@ class CPythonOrderedDictTests(OrderedDictTests, unittest.TestCase):
                     self.assertEqual(list(it), expected)
 
 
+@unittest.skipIf(c_coll, "skip pure-python test if C impl is present")
 class PurePythonOrderedDictSubclassTests(PurePythonOrderedDictTests):
 
     module = py_coll
@@ -764,6 +766,7 @@ class CPythonOrderedDictSubclassTests(CPythonOrderedDictTests):
         pass
 
 
+@unittest.skipIf(c_coll, "skip pure-python test if C impl is present")
 class PurePythonGeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
 
     @classmethod
@@ -787,6 +790,7 @@ class CPythonGeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
         self.assertRaises(KeyError, d.popitem)
 
 
+@unittest.skipIf(c_coll, "skip pure-python test if C impl is present")
 class PurePythonSubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
 
     @classmethod
diff --git a/third_party/python/Lib/test/test_pickle.py b/third_party/python/Lib/test/test_pickle.py
index 02826f055..dfde11e18 100644
--- a/third_party/python/Lib/test/test_pickle.py
+++ b/third_party/python/Lib/test/test_pickle.py
@@ -502,15 +502,11 @@ def test_main():
             tests.extend([CPickleTests, CUnpicklerTests])
         support.run_unittest(*tests)
     else:
-        tests = [PyPickleTests, PyUnpicklerTests, PyPicklerTests,
-                 PyPersPicklerTests, PyIdPersPicklerTests,
-                 PyDispatchTableTests, PyChainDispatchTableTests,
-                 CompatPickleTests]
+        tests = []
         if has_c_implementation:
             tests.extend([CPickleTests, CUnpicklerTests, CPicklerTests,
                           CPersPicklerTests, CIdPersPicklerTests,
                           CDumpPickle_LoadPickle, DumpPickle_CLoadPickle,
-                          PyPicklerUnpicklerObjectTests,
                           CPicklerUnpicklerObjectTests,
                           CDispatchTableTests, CChainDispatchTableTests,
                           InMemoryPickleTests, SizeofTests])
diff --git a/third_party/python/python.mk b/third_party/python/python.mk
index f286c192b..69e9a214e 100644
--- a/third_party/python/python.mk
+++ b/third_party/python/python.mk
@@ -1285,23 +1285,6 @@ THIRD_PARTY_PYTHON_PYTEST_A_PYS =						\
 	third_party/python/Lib/test/support/script_helper.py			\
 	third_party/python/Lib/test/support/testresult.py			\
 	third_party/python/Lib/test/test_dummy_thread.py			\
-	third_party/python/Lib/test/test_json/test_decode.py			\
-	third_party/python/Lib/test/test_json/test_default.py			\
-	third_party/python/Lib/test/test_json/test_dump.py			\
-	third_party/python/Lib/test/test_json/test_encode_basestring_ascii.py	\
-	third_party/python/Lib/test/test_json/test_enum.py			\
-	third_party/python/Lib/test/test_json/test_fail.py			\
-	third_party/python/Lib/test/test_json/test_float.py			\
-	third_party/python/Lib/test/test_json/test_indent.py			\
-	third_party/python/Lib/test/test_json/test_pass1.py			\
-	third_party/python/Lib/test/test_json/test_pass2.py			\
-	third_party/python/Lib/test/test_json/test_pass3.py			\
-	third_party/python/Lib/test/test_json/test_recursion.py			\
-	third_party/python/Lib/test/test_json/test_scanstring.py		\
-	third_party/python/Lib/test/test_json/test_separators.py		\
-	third_party/python/Lib/test/test_json/test_speedups.py			\
-	third_party/python/Lib/test/test_json/test_tool.py			\
-	third_party/python/Lib/test/test_json/test_unicode.py			\
 	third_party/python/Lib/test/test_warnings/data/import_warning.py	\
 	third_party/python/Lib/test/test_warnings/data/stacklevel.py		\
 	third_party/python/Lib/test/testcodec.py				\
@@ -1872,6 +1855,7 @@ THIRD_PARTY_PYTHON_PYTEST_PYMAINS =						\
 	third_party/python/Lib/test/test_iter.py				\
 	third_party/python/Lib/test/test_iterlen.py				\
 	third_party/python/Lib/test/test_itertools.py				\
+	third_party/python/Lib/test/test_json/__main__.py			\
 	third_party/python/Lib/test/test_kdf.py					\
 	third_party/python/Lib/test/test_keyword.py				\
 	third_party/python/Lib/test/test_keywordonlyarg.py			\
@@ -2537,6 +2521,10 @@ o/$(MODE)/third_party/python/Lib/test/test_iter.py.runs: \
 		o/$(MODE)/third_party/python/pythontester.com.dbg
 	@$(COMPILE) -ACHECK -tT$@ $(PYHARNESSARGS) $< -m test.test_iter $(PYTESTARGS)
 
+o/$(MODE)/third_party/python/Lib/test/test_json/__main__.py.runs: \
+		o/$(MODE)/third_party/python/pythontester.com.dbg
+	@$(COMPILE) -ACHECK -tT$@ $(PYHARNESSARGS) $< -m test.test_json $(PYTESTARGS)
+
 o/$(MODE)/third_party/python/Lib/test/test_tarfile.py.runs: \
 		o/$(MODE)/third_party/python/pythontester.com.dbg
 	@$(COMPILE) -ACHECK -tT$@ $(PYHARNESSARGS) $< -m test.test_tarfile $(PYTESTARGS)