The heterocycle in the title compound {systematic name: (5S)-5-[(1S)-1-methyl-prop-yl]pyrrolidine-2,4-dione}, C(8)H(13)NO(2), is planar (r.m.s. deviation for all non-H atoms = 0.008 Å). The crystal structure is stabilized by N-H⋯O hydrogen bonding.