diff --git a/migen/test/support.py b/migen/test/support.py
index 913462acd..e99cfb2c4 100644
--- a/migen/test/support.py
+++ b/migen/test/support.py
@@ -9,7 +9,7 @@ class SimBench(Module):
 		if self.callback is not None:
 			return self.callback(self, s)
 
-class SimCase(unittest.TestCase):
+class SimCase:
 	TestBench = SimBench
 
 	def setUp(self, *args, **kwargs):
diff --git a/migen/test/test_coding.py b/migen/test/test_coding.py
index de0980500..2d0f53d9d 100644
--- a/migen/test/test_coding.py
+++ b/migen/test/test_coding.py
@@ -5,7 +5,7 @@ from migen.genlib.coding import *
 
 from migen.test.support import SimCase, SimBench
 
-class EncCase(SimCase):
+class EncCase(SimCase, unittest.TestCase):
 	class TestBench(SimBench):
 		def __init__(self):
 			self.submodules.dut = Encoder(8)
@@ -29,7 +29,7 @@ class EncCase(SimCase):
 				self.assertEqual(i, 1<<o)
 		self.run_with(cb, 256)
 
-class PrioEncCase(SimCase):
+class PrioEncCase(SimCase, unittest.TestCase):
 	class TestBench(SimBench):
 		def __init__(self):
 			self.submodules.dut = PriorityEncoder(8)
@@ -55,7 +55,7 @@ class PrioEncCase(SimCase):
 				self.assertGreaterEqual(i, 1<<o)
 		self.run_with(cb, 256)
 
-class DecCase(SimCase):
+class DecCase(SimCase, unittest.TestCase):
 	class TestBench(SimBench):
 		def __init__(self):
 			self.submodules.dut = Decoder(8)
diff --git a/migen/test/test_fifo.py b/migen/test/test_fifo.py
index c66f8d5da..f9b789d51 100644
--- a/migen/test/test_fifo.py
+++ b/migen/test/test_fifo.py
@@ -5,7 +5,7 @@ from migen.genlib.fifo import SyncFIFO, AsyncFIFO
 
 from migen.test.support import SimCase, SimBench
 
-class SyncFIFOCase(SimCase):
+class SyncFIFOCase(SimCase, unittest.TestCase):
 	class TestBench(SimBench):
 		def __init__(self):
 			self.submodules.dut = SyncFIFO([("a", 32), ("b", 32)], 2)