According to Variety, rapper-actor Mos Def has been cast opposite Bruce Willis in the upcoming 16 Blocks, directed by Richard Donner for Millennium Films and Willis' Cheyenne Prods.

Richard Wenk script follows an aging cop (Willis) assigned the mundane task of escorting a fast-talking young witness (Def) from police custody to a Gotham courthouse. But forces are at work to stop the pair from making it.

Def co-stars in Touchstone Pictures and Spyglass Entertainment's The Hitchhiker's Guide to the Galaxy, which opens this weekend. He also recently appeared in indie pic The Woodsman and HBO's Something the Lord Made.