Index: _elementtree.c
===================================================================
--- _elementtree.c	(revision 51078)
+++ _elementtree.c	(working copy)
@@ -1523,7 +1523,7 @@
 
     if (self->data) {
         if (self->this == self->last) {
-            Py_DECREF(JOIN_OBJ(self->last->text));
+            Py_XDECREF(JOIN_OBJ(self->last->text));
             self->last->text = JOIN_SET(
                 self->data, PyList_CheckExact(self->data)
                 );