Fixed possible NULL decrefing.

diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 316f9325b64cc4a48039d81bc550b0f207de8f5e..163c87f8b98360dc4b276283b65bf36d7f49f212 100644 (file)
--- 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);
     }
 
 }