The present invention relates to crystalline forms of 3-[5-(2-fluorophenyl)-[1,2,4]oxadiazol-3-yl]-benzoic acid, pharmaceutical compositions and dosage forms comprising the crystalline forms, methods of making the crystalline forms and methods for their use for the treatment, prevention or management of diseases ameliorated by modulation of premature translation termination or nonsense-mediated mRNA decay.