Soul superstar Stevie Wonder is set to perform a special concert in Morocco to celebrate the work of international diplomats who achieved a major milestone for the visually impaired on Thursday (27Jun13).

The Isn't She Lovely hitmaker, who has been blind since birth, vowed to fly to Marrakesh and reward World Intellectual Property Organization officials with a private show if they signed a treaty boosting access to books for those with eyesight problems.

In a video message to delegates converging in the city for a conference, he borrowed the lyrics from his hit Signed, Sealed, Delivered I'm Yours and said, "This is a legacy, a gift to future generations. So let's finalise a new agreement that opens doors to the world's written treasures and moves towards a future where there are no barriers to the expansion of knowledge and enjoyment of culture. Let's get this signed, sealed, delivered, and I'm yours."

The decree was approved by negotiators on Thursday, and now the singer has agreed to stage a celebratory gig at the Palais des Congres on Friday (28Jun13).

The Marrakesh Treaty still has to be ratified by 20 member states of the United Nations before it can go into effect.