diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 5c1a8e9cacb..a8c19ee1a74 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -166,6 +166,9 @@ def test_getwindowsversion(self):
             self.assert_(isinstance(v[3], int))
             self.assert_(isinstance(v[4], str))
 
+    def test_call_tracing(self):
+        self.assertRaises(TypeError, sys.call_tracing, type, 2)
+
     def test_dlopenflags(self):
         if hasattr(sys, "setdlopenflags"):
             self.assert_(hasattr(sys, "getdlopenflags"))
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 10a87611c0d..952f7e59045 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -783,7 +783,7 @@ 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);
 }