Are stocks cheap or expensive? Warren Buffett says it all depends on what happens with interest rates.

“If these interest rates were to continue for 10 years, stocks would be extremely cheap now,” Buffett told CNBC this week. But if rates normalize, stocks valuations would be on the high side, he added. Buffett also said that stocks are cheaper than bonds, which are “very overvalued. … If I had an easy way, and a nonrisk way, of shorting a lot of 20-year or 30-year bonds, I would do it. But that’s not my game. It can’t be done in the quantity that would make sense for us.” Buffett said he’s not sure what will happen with interest rates. But he thinks that if Europe keeps up its quantitative easing bond-buying program, the Federal Reserves should be very cautious about raising rates in the US. “If you have negative rates in Europe, I think there a lot of consequences to raising rates significantly here,” he said.