undefining Class.inherited makes class not subclassable anymore

Hi,
1.) cFoo = rb_define_class ("Foo", rb_cObject);
2.) rb_define_singleton_method (cFoo, "inherited", ...)
3.) rb_undef_method (rb_singleton_class (foo, "inherited"))
4.) rb_define_class (c, "Bar", cFoo)

The fourth call will lead to an error saying:
  "Undefined method 'inherited'"

Is there a way to restore the default Class.inherited method on Foo, so
I can still inherit from Foo, but not call the original inherited method
I defined in step 2?

Thanks,
Tilman

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