The price of dogecoin fell sharply on Thursday morning, sliding below 40 cents per coin, after Tesla CEO and crypto booster Elon Musk announced that the automaker was suspending the use of bitcoin in payments over environmental concerns.

Musk, who previously bought billions in bitcoin for Tesla and has tweeted regularly about dogecoin, said he was concerned by “rapidly increasing use of fossil fuels for Bitcoin mining and transactions.” The price of bitcoin also pulled back following the announcement.

Thursday’s weakness continues a brutal week for dogecoin, the cryptocurrency which started as a joke nearly a decade ago but has risen to prominence this year.

The price of the coin rose to above 70 cents earlier this month according to Coinbase ahead of Musk’s appearance on NBC’s “Saturday Night Live.” However, dogecoin came under pressure once the show began, at one point falling below 50 cents, and Musk described the cryptocurrency as a “hustle.”

Musk is not the only billionaire who has talked about dogecoin in a positive light in recent months, with Mark Cuban saying that people seemed to favor using doge for transactions over other cryptocurrencies, giving it value.

The Dallas Mavericks owner said on Twitter that he would not be following Musk’s latest decision about accepting bitcoin as payment.

“We at Mavs.com will continue to accept BTC/Eth/Doge because we know that replacing Gold as a store of value will help the environment … and … shrinking big bank and coin usage will benefit society and the environment,” Cuban said Wednesday night.

Disclosure: “Saturday Night Live” is a TV show of NBCUniversal, the parent company of CNBC. CNBC owns the exclusive off-network cable rights to “Shark Tank,” which features Mark Cuban as a panelist.