A structure model of the new solid form was obtained in the orthorhombic space group 𝑃2 1 2 1 2 1 with unit cell parameters a = 20.33 ( ). The crystal structure revealed that the form is also an IC of GSF and PEG, with GSF channels extending along the crystallographic c-axis that are isostructural with the GSF nitromethane solvate . The presence of the disordered PEG molecules could again be confirmed by the positive density in the difference potential map.