2-Methyl­sulfanyl-9H-1,3,4-thia­diazolo[2,3-b]quinazolin-9-one

In the title compound, C(10)H(7)N(3)OS(2), the 16 non-H atoms are almost planar (r.m.s. deviation = 0.037 Å) and the S-bound methyl group is syn to the ketone O atom. In the crystal, centrosymmetrically related mol­ecules are connected by pairs of C—H⋯O inter­actions between the ketone O and methyl H atoms. The dimeric aggregates are connected into a linear supra­molecular chain along the b axis via π–π inter­actions occurring between the five-membered and benzene rings [centroid–centroid distance = 3.6123 (9) Å]. The chains assemble into layers in the bc plane via S⋯S inter­actions involving the endocyclic S atoms [S⋯S = 3.4607 (6) and 3.4792 (6) Å].