diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index c9bc4a3..24c4dcb 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -801,7 +801,7 @@ static PyObject *
 sys_call_tracing(PyObject *self, PyObject *args)
 {
 	PyObject *func, *funcargs;
-	if (!PyArg_UnpackTuple(args, "call_tracing", 2, 2, &func, &funcargs))
+	if (!PyArg_ParseTuple(args, "OO!:call_tracing", &func, &PyTuple_Type, &funcargs))
 		return NULL;
 	return _PyEval_CallTracing(func, funcargs);
 }
Index: Lib/test/test_sys.py
===================================================================
--- Lib/test/test_sys.py	(révision 77870)
+++ Lib/test/test_sys.py	(copie de travail)
@@ -433,7 +433,11 @@
         out = p.communicate()[0].strip()
         self.assertEqual(out, '?')
 
+    def test_call_tracing(self):
+        self.assertEqual(sys.call_tracing(str, (10,)), "10")
+        self.assertRaises(TypeError, sys.call_tracing, str, 10)
 
+
 class SizeofTest(unittest.TestCase):
 
     TPFLAGS_HAVE_GC = 1<<14