diff --git a/py65/tests/devices/test_klaus.py b/py65/tests/devices/test_klaus.py
new file mode 100644
index 0000000..d59ab8f
--- /dev/null
+++ b/py65/tests/devices/test_klaus.py
@@ -0,0 +1,64 @@
+import unittest
+import sys
+import py65.devices.mpu65c02
+
+class KlausDormannTests(unittest.TestCase):
+    """Runs Klaus Dormann's 6502-based test suites"""
+
+    def klausTestCase(self, filename, load_addr, pc, success_addr):
+        mpu = self._make_mpu()
+        mpu.pc = pc
+
+        object_code = bytearray(open(filename, "r").read())
+        self._write(mpu.memory, load_addr, object_code)
+
+        while True:
+            old_pc = mpu.pc
+            mpu.step()
+            if mpu.pc == old_pc:
+                break
+
+        assert mpu.pc == success_addr, mpu
+
+    def test6502FunctionalTest(self):
+        self.klausTestCase("6502_functional_test.bin", 0x0, 0x400, 0x3399)
+
+    def test65C02ExtendedOpcodesTest(self):
+        self.klausTestCase("65C02_extended_opcodes_test.bin", 0x0, 0x400, 0x24a8)
+
+    def test6502DecimalTest(self):
+        mpu = self._make_mpu()
+        mpu.pc = 0x1000
+
+        object_code = bytearray(open("6502_decimal_test.bin", "r").read())
+        self._write(mpu.memory, 0x200, object_code)
+
+        # $1000: JSR $0200
+        self._write(mpu.memory, 0x1000, [0x20, 0x00, 0x02])
+
+        while True:
+            mpu.step()
+            if mpu.pc == 0x1003:
+                break
+        assert mpu.memory[0x0b] == 0
+
+    # Test Helpers
+
+    def _write(self, memory, start_address, bytes):
+        memory[start_address:start_address + len(bytes)] = bytes
+
+    def _make_mpu(self, *args, **kargs):
+        klass = self._get_target_class()
+        mpu = klass(*args, **kargs)
+        if 'memory' not in kargs:
+            mpu.memory = 0x10000 * [0xAA]
+        return mpu
+
+    def _get_target_class(self):
+        return py65.devices.mpu65c02.MPU
+
+def test_suite():
+    return unittest.findTestCases(sys.modules[__name__])
+
+if __name__ == '__main__':
+    unittest.main(defaultTest='test_suite')