We present an experimental characterization of a heralded single-photon source based on spontaneous four-wave mixing in a single-mode microstructure fiber. We measure the second-order correlation function g((2))(0) to be far below the classical, Poissonian limit of 1 over a broad spectral range. With single-spatial-mode output, such a spectrally bright and broad fiber-based heralded single-photon source is suitable for a variety of quantum-information applications.