diff -r 0f9113e1b541 Lib/test/test_exceptions.py
--- a/Lib/test/test_exceptions.py	Sun Feb 10 19:27:37 2013 +0200
+++ b/Lib/test/test_exceptions.py	Sun Feb 10 18:54:44 2013 +0000
@@ -479,6 +479,18 @@
         except AssertionError as e:
             self.assertEqual(str(e), "(3,)")
 
+    def test_bad_exception_clearing(self):
+        # See issue 16445: use of Py_XDECREF instead of Py_CLEAR in
+        # BaseException_set_message gave a possible way to segfault the
+        # interpreter.
+        class Nasty(str):
+            def __del__(message):
+                del e.message
+
+        e = ValueError(Nasty("msg"))
+        e.args = ()
+        del e.message
+
 
 # Helper class used by TestSameStrAndUnicodeMsg
 class ExcWithOverriddenStr(Exception):
diff -r 0f9113e1b541 Objects/exceptions.c
--- a/Objects/exceptions.c	Sun Feb 10 19:27:37 2013 +0200
+++ b/Objects/exceptions.c	Sun Feb 10 18:54:44 2013 +0000
@@ -349,8 +349,7 @@
             if (PyDict_DelItemString(self->dict, "message") < 0)
                 return -1;
         }
-        Py_XDECREF(self->message);
-        self->message = NULL;
+        Py_CLEAR(self->message);
         return 0;
     }