Warren Buffett is not in favor of investing in bitcoin and isn't holding his thoughts back.

According to CNBC's Becky Quick, Buffett told her before Berkshire Hathaway's annual meeting on Saturday that bitcoin is "probably rat poison squared."

Buffett, who is the CEO of Berkshire Hathaway, has historically been a harsh critic on the cryptocurrency. According to CNN, Buffett has compared bitcoin to gold in the past. He said both forms of currency are speculative and don't yield the same earnings and dividends as stock. During Saturday's meeting, the Berkshire Hathaway CEO said, "If you had bought gold at the time of Christ and you figure the compound rate on it, it's a couple tenths of a percent." In response to an audience question, he also said that bitcoin and other forms of cryptocurrency "will come to bad endings."

Bitcoin fell almost 6% on Sunday and fell an additional 2% on Monday, reports CNN

Berkshire vice chairman Charlie Munger said to Buffett during the meeting, "I like cryptocurrencies a lot less than you do. To me, it's just dementia. It's like somebody else is trading turds and you decide you can't be left out."

In a report written on Monday, Nigel Green, who is the CEO of financial consulting firm deVere Group said, "What I do find monumentally baffling is that two of the world's most successful investors cannot see the intrinsic value of some form of cryptocurrency. Do they honestly believe that there is no place for, and no value of, digital, global currencies in an increasingly digitalized and globalized world?"

Buffett is, however, in good company with his hate on bitcoin. Bill Gates has rejected the cryptocurrency and told CNBC’s Squawk Box on Monday, "Bitcoin and ICOs, I believe completely [they're some] of the crazier, speculative things."