Crystalline solid forms and the amorphous form of the anti-HCV compound 5-(3,3-dimethylbutyn-1-yl)-3-[(cis-4-hydroxy-4-{[(3S)-tetrahydrofuran-3-yloxy]methyl}cyclohexyl){[(1R)-4-methylcyclohex-3-en-1-yl]carbonyl}amino]thiophene-2-carboxylic acid (Compound I) were prepared and characterized in the solid state: Also provided are processes of manufacture and methods of using the crystalline forms.