US private sector employment rose by 178,000 jobs in May from April as finding workers becomes increasingly difficult, according to the ADP National Employment Report. April’s gain was revised downward to 163,000 from the initially reported 204,000.

“The hot job market has cooled slightly as the labor market continues to tighten,” said Ahu Yildirmaz, VP and co-head of the ADP Research Institute. “Healthcare and professional services remain a model of consistency and continue to serve as the main drivers of growth in the services sector and the broader labor market as well.”

April’s jobs gain was below forecasts from economists polled by Bloomberg, which had expected ADP to tally 190,000 private-sector job gains, according to USA Today. Monthly job growth averaged a healthy 200,000 through the first four months of the year, but that’s likely to slow.

The number of goods-producing jobs rose by 64,000 in May on gains of 39,000 construction jobs, 14,000 manufacturing jobs and 11,000 natural resources/mining jobs.

Service-providing jobs rose by 114,000 in May, including by 61,000 jobs in professional/business services; 35,000 jobs in education/health services; and 33,000 jobs in leisure/hospitality.

Jobs in trade/transportation/utilities posted the only decline, falling by 23,000.

Large businesses added 56,000 jobs in May, midsize businesses added 84,000 jobs and small businesses added 38,000 jobs.

“Job growth is strong, but slowing, as businesses are unable to fill a record number of open positions,” said Mark Zandi, chief economist of Moody’s Analytics. “Wage growth is accelerating in response, most notably for young, new entrants and those changing jobs. Finding workers is increasingly becoming businesses’ number one problem.”