Wholesale prices rose more than expected in April, according to new data released Tuesday. However, when analyzing revisions to March’s Producer Price Index, Federal Reserve Chair Jerome Powell argued the release was “mixed.”

“We had a producer price index reading just a couple of hours ago, and I would say it’s actually quite mixed,” Powell said during a panel in Amsterdam. “You know, the headline numbers were higher, but they were backward revisions.”

He added: “I wouldn’t call it hot, I would call it sort of mixed.”

Wholesale prices increased 0.5% month-over-month in April, above the 0.3% consensus had expected, per the latest release of the Producer Price Index, which measures prices producers receive for goods produced.

“Core” PPI, which strips out the volatile food and energy categories, also rose 0.5%, above estimates for a 0.2% increase. Also, in the release, March’s monthly price increase was revised lower to a decrease of 0.1% from an initial reading of a 0.2% increase.

Speaking broadly about inflation, Powell said Tuesday his confidence in inflation continuing to cool is not as high as it was at the start of the year and that the central bank will need to be patient before lowering interest rates.

“We did not expect this to be a smooth road, but these [inflation readings] were higher than I think anybody expected,” Powell said. “What that has told us is that we’ll need to be patient and let restrictive policy do its work.”