diff -r fe189b8bd3ab Objects/exceptions.c
--- a/Objects/exceptions.c	Fri Aug 05 01:51:39 2016 +0000
+++ b/Objects/exceptions.c	Fri Aug 05 17:55:37 2016 +0800
@@ -230,7 +230,7 @@
         return -1;
     }
 
-    Py_XINCREF(tb);
+    Py_INCREF(tb);
     Py_XSETREF(self->traceback, tb);
     return 0;
 }
@@ -985,7 +985,7 @@
     return 0;
 
 error:
-    Py_XDECREF(args);
+    Py_DECREF(args);
     return -1;
 }
 
@@ -1065,8 +1065,7 @@
     }
     if (self->myerrno && self->strerror)
         return PyUnicode_FromFormat("[Errno %S] %S",
-                                    self->myerrno ? self->myerrno: Py_None,
-                                    self->strerror ? self->strerror: Py_None);
+                                    self->myerrno, self->strerror);
     return BaseException_str((PyBaseExceptionObject *)self);
 }