The difference in packing of the two ICs arises from the conformational differences of the GSF molecules stemming from the free rotation of the cyclohexanone ring with respect to the benzofuran ring moiety and has been well documented previously in the study of GSF solvates . To the best of our knowledge, this is the first time polymorphism has been observed within ICs built from the same combination of clinical drug and polymer. We propose to name the first reported IC as GSF-PEG IC1 and the novel IC discovered in this work as GSF-PEG IC2.