Small businesses are still struggling to find workers. They’re also paying the ones they do have more or offering other incentives, according to the latest survey by payroll and human resources provider ADP.

Jobs did rebound for large and midsized businesses last month, per ADP’S tally. Total jobs were up 128,000 compared with

April. But small businesses, defined as those with fewer than 50 employees, shed 91,000 employees compared with the prior month.

The shortage and accompanying labor costs are a growing concern for small businesses, according to ADP’S quarterly Small Business at Work Survey of small firms. Fifty-five percent of small businesses cited hiring as their top challenge in April, up from from 39% in January. That was a bigger concern than higher costs, supply chain disruption and the economy.

For businesses with 50 to 499 employees, 79% said hiring was a top challenge, up from 62%. Forty percent cited staff retention, up from 34%.

“One reason for today’s high quit rates are wages,” said Nela Richardson, ADP chief economist. “Workers know they can get better pay by switching jobs, so they do.”

Companies that can are offering signing bonuses and higher pay to maintain their current workforce and attract new hires. About 25% of companies surveyed said they’re offering financial incentives to keep people on board.

Smaller companies that might not be able to raise wages are offering things like flexible work hours and schedules, retirement plans and life insurance.