Index: _tkinter.c
===================================================================
--- _tkinter.c	(revision 67233)
+++ _tkinter.c	(working copy)
@@ -844,6 +844,12 @@
 	return 0;
 }
 
+static int
+PyTclObject_nonzero(PyTclObject *self)
+{
+    return Tcl_GetCharLength(self->value) ? 1 : 0;
+}
+
 PyDoc_STRVAR(get_typename__doc__, "name of the Tcl type");
 
 static PyObject*
@@ -868,6 +874,20 @@
 	{0}
 };
 
+static PyNumberMethods PyTclObject_as_number = {
+    0,                              /* nb_add */
+    0,                              /* nb_subtract */
+    0,                              /* nb_muliply */
+    0,                              /* nb_divide */
+    0,                              /* nb_remainder */
+    0,                              /* nb_divmod */
+    0,                              /* nb_power */
+    0,                              /* nb_negative */
+    0,                              /* nb_positive */
+    0,                              /* nb_absolute */
+    (inquiry)PyTclObject_nonzero    /* nb_nonzero */
+};
+
 statichere PyTypeObject PyTclObject_Type = {
 	PyObject_HEAD_INIT(NULL)
 	0,			/*ob_size*/
@@ -881,7 +901,7 @@
 	0,			/*tp_setattr*/
 	(cmpfunc)PyTclObject_cmp,	/*tp_compare*/
 	(reprfunc)PyTclObject_repr,	/*tp_repr*/
-	0,			/*tp_as_number*/
+	&PyTclObject_as_number,		/*tp_as_number*/
 	0,			/*tp_as_sequence*/
 	0,			/*tp_as_mapping*/
 	0,			/*tp_hash*/