diff -r a39d2223be23 Doc/c-api/typeobj.rst
--- a/Doc/c-api/typeobj.rst	Sun Jun 23 15:53:09 2013 +0200
+++ b/Doc/c-api/typeobj.rst	Sun Jun 23 17:02:10 2013 +0200
@@ -116,7 +116,8 @@
    If no dot is present, the entire :attr:`tp_name` field is made accessible as the
    :attr:`__name__` attribute, and the :attr:`__module__` attribute is undefined
    (unless explicitly set in the dictionary, as explained above).  This means your
-   type will be impossible to pickle.
+   type will be impossible to pickle. Additionally, it will not be listed in
+   module documentations created with pydoc.
 
    This field is not inherited by subtypes.
 
diff -r a39d2223be23 Doc/extending/newtypes.rst
--- a/Doc/extending/newtypes.rst	Sun Jun 23 15:53:09 2013 +0200
+++ b/Doc/extending/newtypes.rst	Sun Jun 23 17:02:10 2013 +0200
@@ -125,7 +125,9 @@
 
 Note that the name is a dotted name that includes both the module name and the
 name of the type within the module. The module in this case is :mod:`noddy` and
-the type is :class:`Noddy`, so we set the type name to :class:`noddy.Noddy`. ::
+the type is :class:`Noddy`, so we set the type name to :class:`noddy.Noddy`.
+One side effect of using an undotted name is that the pydoc documentation tool
+will not list the new type in the module documentation. ::
 
    sizeof(noddy_NoddyObject),  /* tp_basicsize */
 
diff -r a39d2223be23 Objects/typeobject.c
--- a/Objects/typeobject.c	Sun Jun 23 15:53:09 2013 +0200
+++ b/Objects/typeobject.c	Sun Jun 23 17:02:10 2013 +0200
@@ -4143,6 +4143,9 @@
     _Py_AddToAllObjects((PyObject *)type, 0);
 #endif
 
+    if (type->tp_name == NULL)
+        goto error;
+
     /* Initialize tp_base (defaults to BaseObject unless that's us) */
     base = type->tp_base;
     if (base == NULL && type != &PyBaseObject_Type) {