An 80-year-old heir to the Hermès empire wants to leave at least half of his roughly €12 billion ($13 billion) fortune to his former gardener after previously pledging it to his charity, according to reports.

Nicolas Puech has started the process to adopt the 51-year-old man from a "modest Moroccan family" and designate him as his heir, Swiss newspaper Tribune de Geneve reported.

Puech's plan reportedly includes canceling a contract that states his fortune would go to a charitable foundation.

The potential heir is described in Swiss media as Puech's "servant, former gardener and handyman."

Puech, who is unmarried and childless, reportedly owns a 5.7% stake in Hermès, currently valued at around €211 billion ($230.8 billion), according to the company's latest annual report. This means the reclusive billionaire's stake in the company is worth around $13 billion. 

Initially, Puech had promised to leave his wealth to the Isocrates Foundation, a charity he established in 2011 to support public interest journalism and foster civic debate, according to the Swiss outlet.

Following the report, the Isocrates Foundation released a statement expressing its opposition to the cancellation of its contract with Puech.

"From a legal point of view, a unilateral cancellation of the contract of inheritance seems void and unfounded," the charitable foundation said in the statement shared with CNN Wednesday.

The charity said it is open to discussions with its founder while awaiting legal resolution.

The inheritance contract reportedly states that Puech's shares in Hermès would benefit the foundation unless he had a child.

In the event of parenthood, the child would be entitled to a share, with at least 50% guaranteed for a son.

According to MarketWatch, Swiss law requires those who wish to adopt adults to have lived with the adoptee for at least a year when they were a minor.

It's not clear if the gardener had lived with Puech when he was still a minor.

Puech would not be the first wealthy individual to make an unconventional choice in bequeathing fortunes.

In 2007, Luis Carlos de Noronha Cabral da Camara, who is of noble Portuguese lineage, picked out 70 random names from a phone book and left them his bank accounts, 12-room apartment in Lisbon, house in Portugal, luxury car and two motorcycles, The Guardian reported.

Earlier this year, The New York Times reported that a New Hampshire man left his entire $3.8 million fortune to the town he'd lived in for decades.

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