From 3ec5f421c58e2785edbb8ee3e4a575491bb0e7c2 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Fri, 28 Oct 2016 12:14:34 +0300
Subject: [PATCH] Fixed possible NULL decrefing.

---
 Modules/_tkinter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 316f9325b64..163c87f8b98 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -1779,7 +1779,7 @@ var_perform(VarEvent *ev)
         PyErr_NormalizeException(&exc, &val, &tb);
         *(ev->exc_type) = exc;
         *(ev->exc_val) = val;
-        Py_DECREF(tb);
+        Py_XDECREF(tb);
     }
 
 }