Customers can now buy their new Tesla with Bitcoin, said Elon Musk on Twitter, delivering on the promise he made in early February.

Tesla’s …Technoking added that the carmaker is going to retain Bitcoin payments as Bitcoin and will not convert them into a fiat currency. So far, the ability to buy a new Tesla with Bitcoin is limited to the US market only, but the service will become available in other markets later this year.

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Bitcoin prices increased more than 4 percent after Musk’s announcement and is trading at $56,054 at the time of writing.

Tesla’s cars will continue to be priced in US dollars, with customers offered the option to pay the equivalent amount in Bitcoin. Due to the cryptocurrency’s volatility, customers will have to pay the requested amount within a given time limit.

Tesla revealed last month that they invested $1.5 billion in Bitcoin without revealing when exactly. Prices back then for the cryptocurrency were at around $33,000, which means that Tesla’s investment has increased in value by roughly $1.2 billion today.

Other mainstream companies that accept bitcoin as payment, such as AT&T and Microsoft, typically use specialist payment processors that convert cryptocurrency into fiat currency, Reuters reports.

Musk has been a supporter of cryptocurrencies like Bitcoin and Dogecoin despite their poor environmental credentials, criticizing conventional currencies for having “negative real interest, only a fool wouldn’t look elsewhere”.