Walmart Inc. is offering special bonuses to many warehouse employees to work every hour they are scheduled and, in some cases giving temporary pay raises, as the country’s biggest retailer ramps up for the holiday shopping season with a tight labor market and stretched supply chains.

The majority of Walmart’s 190 U.S. warehouses are offering the weekly bonus or pay raises. The bonuses and raises vary by location and job type, according to a person familiar with the situation.

Some workers have been offered $1,000 over four weeks for not skipping any scheduled shifts during the second half of the summer. Last week, some workers were also offered temporary pay raises of several dollars an hour through January 2022, said this person.

Walmart aims to acknowledge the efforts of employees with incentives, and provide opportunity in a competitive job market, a Walmart spokesman said. The retailer’s distribution warehouses “continue to see high volume as we are preparing for peak season,” he said. Walmart is the country’s largest private employer with 1.6 million U.S. workers, most of which are hourly workers in stores and warehouses.

Retailers and other businesses are straining to hire workers and face a global supply chain snarled by the pandemic and other factors as demand for many products and services grows.