Index: Python/sysmodule.c
===================================================================
--- Python/sysmodule.c	(revision 66791)
+++ Python/sysmodule.c	(working copy)
@@ -802,7 +802,7 @@
 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	(revision 66791)
+++ Lib/test/test_sys.py	(working copy)
@@ -210,6 +210,9 @@
             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"))