Employers have plenty of reasons to bring Millennials on board. Twenty-something workers are stingy with vacation days, obsessively hard-working, and according to a recent study by British researchers, hesitant to switch jobs [PDF]. As Bloomberg reports, that level of loyalty can end up costing them in the long run.

For the study, the think tank Resolution Foundation analyzed the employment trends of workers born in the mid-1980s in the U.K. They found that just one in 25 subjects had changed jobs before turning 30. The rate for employees born in the mid-1970s was double that.

Rather than rewarding workers for sticking around, companies often take Millennials for granted. According to the research, this age group has virtually stopped receiving annual raises. In the past, the average annual salary increase for young workers was around 4 percent.

By staying with a job that doesn’t reward them for their commitment, younger employees are leaving a lot of money on the table. The ADP Research Institute found that full-time workers who job-hopped received a 4.5 percent wage boost. According to Laura Gardiner of the Resolution Foundation, the rate is more than triple that for employees who trade up jobs in their mid-twenties. She tells Bloomberg that her report indicates that Millennials are prioritizing job security over higher salaries—not surprising when you consider the astronomical student debt and highly competitive job market new college graduates face.

[h/t Bloomberg]