In 2020, BrunatDudasTaylor showed that the decomposition matrix of unipotent ℓ-blocks of a nite reductive group in good characteristic has unitriangular shape, under some conditions on the prime ℓ, in particular ℓ being good. We extend this result to ℓ bad by adapting their proof to include the ℓ-special classes dened by Chaneb.