Louistef (Pty) Ltd leased immovable property from the Louis Snyders Familie Trust and operated a fuel filling station thereon. Under the transitional provisions of the Petroleum Products Act 120 of 1977, Louistef was issued with a site licence and a retail licence in 2008. In March 2014, Louistef and the trust concluded a written agreement in terms of which Louistef sold its site licence to the trust for R1 million. The Controller of Petroleum Products approved the transfer and issued a site licence in the trust’s name. After the transfer, the trust contended that the agreement was invalid and unenforceable on the basis that a site licence was not a merchantable merx and that the parties had been under a common mistake. The trust sought a declaratory order to that effect in the High Court. Louistef opposed the application and counter-applied for payment of the purchase price. The High Court found in favour of the trust. Louistef appealed to the Supreme Court of Appeal.