US Securities and Exchange Commission (SEC) Chairman Gary Gensler has cast further doubt on cryptocurrencies, saying he doesn’t believe they are viable long-term.

Gensler has been working to establish the SEC as THE US regulatory authority for crypto. While some critics believe it’s an overreach, Gensler maintains that cryptocurrencies have much in common with securities.

In a new interview with The Washington Post, Gensler throws more cold water on the cryptocurrency market, saying he doesn’t believe it has much of a long-term future.

“History tells us that private forms of money don’t last long,” he said.

Gensler has a more positive view of the blockchain technology behind cryptocurrencies, crediting Bitcoin creator Satoshi Nakamoto with innovating and creating a catalyst for change in the financial markets. When referring to Nakamoto, he even used the respectful term “Nakamoto-san,” and said the innovation he created is helping bolster payment systems with distributed ledgers and decentralized lending.

Nonetheless, one thing is clear: If Gensler has his way, significant crypto regulation is on the horizon in the US. Gensler is a firm believer that the potential for things to go wrong warrants taking proactive measures to regulate the industry and head off potential issues.

“I don’t think it’s a good idea to wait until there’s a spill in aisle three,” he said.