  A five-dimensional dyonic black hole in Type-I theory is considered that is
extremal but non-supersymmetric. It is shown that the Bekenstein-Hawking
entropy of this black hole counts precisely the microstates of a D-brane
configuration with the same charges and mass, even though there is no apparent
supersymmetric nonrenormalization theorem for the mass. A similar result is
known for the entropy at the stretched horizon of electrically charged,
extremal, but non-supersymmetric black holes in heterotic string theory. It is
argued that classical nonrenormalization of the mass may partially explain this
result.
