The title compound, C11H18O5, was isolated from a liquid culture of Pestalotiopsis sp. In the mol-ecule, the pyran-2-one ring assumes a half-chair conformation. The two terminal C atoms of the pentyl group were refined as disordered over two sets of sites, with refined occupancies of 0.881 (10) and 0.119 (10). In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds forming a three-dimensional network.