Employers posted more job openings in June than they did a month earlier, and the number of U.S. workers who quit their jobs climbed, signaling steady improvement in the labor market.

Employers had 4.7 million job openings on the last business day of June, up from 4.6 million a month earlier, the Labor Department said Tuesday. The number of workers hired clicked up to 4.8 million from May’s 4.7 million.

Meantime, 2.53 million Americans quit a job in June, up from 2.49 million who did so in May.

Federal Reserve Chairwoman Janet Yellen, has pointed to the monthly report, called Job Openings and Labor Turnover Survey, or JOLTS—as a key measure to assess the jobs market.