The title compound, C₈H₈N₄O₃S, is planar chiral in the solid state. It crystallizes with three independent molecules in the asymmetric unit, two of which have the same chirality and the third is the opposite enantiomer. Partial inversion twinning is present in the crystal which was examined. All three molecules are connected via hydrogen bonds between the amide groups, forming a helix around the b axis of the unit cell.