diff --git a/ntunnel.py b/ntunnel.py
index aff73ef..1cc1de4 100644
--- a/ntunnel.py
+++ b/ntunnel.py
@@ -316,21 +316,34 @@ class TestMain(unittest.TestCase):
 		shutil.rmtree(self.basetempdir)
 		self.tempdir = None
 
-	def test_noargs(self):
-		sys.argv = [ 'prog' ]
+	@async_test
+	async def test_noargs(self):
+		proc = await self.run_with_args()
 
-		with self.assertRaises(SystemExit) as cm:
-			main()
+		await proc.wait()
 
 		# XXX - not checking error message
 
 		# And that it exited w/ the correct code
-		self.assertEqual(5, cm.exception.code)
+		self.assertEqual(proc.returncode, 5)
+
+	def run_with_args(self, *args):
+		return asyncio.create_subprocess_exec(sys.executable,
+		    __file__, *args,
+		    stdout=asyncio.subprocess.PIPE,
+		    stderr=asyncio.subprocess.PIPE)
 
-	def test_genkey(self):
+	def test_both(self):
+		pass
+
+	@async_test
+	async def test_genkey(self):
 		# that it can generate a key
-		sys.argv = [ 'prog', 'genkey', 'somefile' ]
-		main()
+		proc = await self.run_with_args('genkey', 'somefile')
+
+		await proc.wait()
+
+		self.assertEqual(proc.returncode, 0)
 
 		with open('somefile.pub', encoding='ascii') as fp:
 			lines = fp.readlines()
@@ -347,13 +360,17 @@ class TestMain(unittest.TestCase):
 			self.assertIsInstance(key, x448.X448PrivateKey)
 
 		# that a second call fails
-		with self.assertRaises(SystemExit) as cm:
-			main()
+		proc = await self.run_with_args('genkey', 'somefile')
 
-		# XXX - not checking error message
+		await proc.wait()
+
+		stdoutdata, stderrdata = await proc.communicate()
+
+		self.assertFalse(stdoutdata)
+		self.assertEqual(b'failed to create somefile.pub, file exists.\n', stderrdata)
 
 		# And that it exited w/ the correct code
-		self.assertEqual(1, cm.exception.code)
+		self.assertEqual(proc.returncode, 1)
 
 class TestNoiseFowarder(unittest.TestCase):
 	def setUp(self):