diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 2161706..d0aa59f 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1254,11 +1254,11 @@
    .. index:: single: __len__() (mapping object method)
 
    Called to implement truth value testing and the built-in operation
-   ``bool()``; should return ``False`` or ``True``, or their integer equivalents
-   ``0`` or ``1``.  When this method is not defined, :meth:`__len__` is called,
-   if it is defined, and the object is considered true if its result is nonzero.
-   If a class defines neither :meth:`__len__` nor :meth:`__bool__`, all its
-   instances are considered true.
+   ``bool()``; should return ``False`` or ``True``.  When this method is not
+   defined, :meth:`__len__` is called, if it is defined, and the object is
+   considered true if its result is nonzero.  If a class defines neither
+   :meth:`__len__` nor :meth:`__bool__`, all its instances are considered
+   true.
 
 
 .. _attribute-access:
diff --git a/Misc/NEWS b/Misc/NEWS
index 2e04011..7cc3f36 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,10 @@
 Core and Builtins
 -----------------
 
+- Issue #6428: Since Python 3.0, the __bool__ method must return a bool
+  object, and not an int.  Fix the corresponding error message, and the
+  documentation.
+
 - The deprecated PyCObject has been removed.
 
 - Issue #6347: Include inttypes.h as well as stdint.h in pyport.h.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 0e79542..60483e7 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -4807,10 +4807,8 @@
 			}
 			else {
 				PyErr_Format(PyExc_TypeError,
-					     "%s should return "
-					     "bool or int, returned %s",
-					     (using_len ? "__len__"
-					                : "__bool__"),
+					     "__bool__ should return "
+					     "bool, returned %s",
 					     Py_TYPE(temp)->tp_name);
 				result = -1;
 			}