Described herein are crystalline forms of (3,5-dibromo-4-hydroxyphenyl)(2-(1-hydroxyethyl)benzofuran-3-yl-4,5,6,7-d4)methanone, and solvates thereof.L'invention concerne des formes cristallines de (3,5-dibromo-4-hydroxyphényl) (2- (1-hydroxyéthyl) benzofuran-3-yl-4,5,6,7-d4)méthanone, et des solvates de celles-ci.