Economic activity in the manufacturing sector expanded in January but at a slightly slower pace than December, according to the Institute for Supply Management’s purchasing managers index for US manufacturing. January’s index reading was 59.1, down 0.2 of a percentage point from December’s reading of 59.3.

Any reading above 50% generally indicates improving conditions.

However, the employment portion of the index fell to a reading of 54.2 in January from 58.1 in December.

“Employment expansion remains strong, but difficulties across the supply chain continue to constrain production output,” said Timothy Fiore, chair of the Institute for Supply Management manufacturing business survey committee.

The manufacturing sector had a stellar year in 2017 and economists are watching closely to see if the good times continue, MarketWatch reported.