The reaction of 2‐hydrazinobenzothiazole (1) with ethyl acetoacetate has twice been reported to yield a fused triazepinobenzothiazolone, namely, 3‐methyl[1,2,4]triazepino[3,4‐b]benzothiazol‐5(4H)‐one (4). We have repeated this work and reassigned the reaction product as 2‐(2‐benzothiazolyl)‐1,2‐dihydro‐5‐methyl‐3H‐pyrazol‐3‐one (5) on the basis of X‐ray crystallography.