What does the former head of the Federal Reserve think of a digital currency that operates outside the control of central banks? The answer, unsurprisingly, is not much.
“Bitcoin is an attempt to replace fiat currency and evade regulation and government intervention. I don’t think that’s going to be a success,” Bernanke said on Monday afternoon in Toronto.
While addressing a conference hosted by the blockchain firm Ripple, Bernanke described bitcoin as a “mostly speculative venture” that “hasn’t shown itself to be a real transactional currency.”
He also dismissed the idea, espoused by some die-hard bitcoin advocates, that the digital currency could be a rival to traditional government-controlled money.
“Eventually governments will take any action they need to prevent [that],” he said.
His comments can be seen as a rebuke to some crypto-currency enthusiasts, who are skeptical of central banks and who recently photo-bombed the current Federal Reserve chair, Janet Yellen, with a “buy bitcoin” sign:
The good news for crypto-currency fans is that Bernanke, who helped steer the U.S. through the depths of the 2008 financial crisis, is not down on all digital money.
He praised Ripple, which provides blockchain software to banks and has its own native currency (known as XRP), for working with regulators.
Get Data Sheet, Fortune’s technology newsletter.
Bernanke also acknowledged that blockchain technology, which relies on disparate computers to create a tamper-proof ledger of transactions, holds considerable promise for global banking systems.
“The Fed, the Bank of England, and Japan are very supportive of these technologies because they’ll improve payment systems,” he said, adding blockchain will be especially effective in expediting cross-border payments.
Bernanke also observed that a blockchain-style system might have averted last year’s debacle in which hackers exploited the SWIFT money transfer system to rob over $80 million from the Central Bank of Bangladesh.
Bernanke’s comments came in the context of a larger discussion of banking and economics with Gene Sperling, a former director of the National Economic Council, and adviser to Presidents Barack Obama and Bill Clinton.
His other notable remarks included a prediction that the Federal Reserve is unlikely to dramatically reduce its balance sheet (“monetary policy works better if the balance sheet is bigger”), and an observation that the Trump Administration is unlikely to deliver major economic stimulus through tax reform.
Meanwhile, the skepticism of bitcoin by Bernanke and other prominent financial figures like Jamie Dimon has done little to dent its price: the currency broke new records last week and is up five-fold from the start of the year. It’s currently trading around $5,600.
This article is part of The Ledger, Fortune’s focus on the intersection of tech and finance. For more coverage, click here.
Learn more about all things crypto with short, easy-to-read lesson cards. Click here for Fortune’s Crypto Crash Course.