A lawsuit accusing PricewaterhouseCoopers LLP of violating U.S. discrimination law by hiring a “stunningly low” number of people over the age of 40 to maintain a youthful culture has been filed in San Francisco.

The lawsuit, filed on Wednesday in federal court, said the London-based accounting company does virtually all of its recruiting for entry-level jobs on college campuses to stock its workforce with millenials. Federal law bars employers from discriminating against workers and job applicants who are 40 and older.

The lawsuit was brought by Steve Rabin, 53, a certified public accountant who said he was turned down for an accounting job at PwC because the company uses recruiting programs that weed out older applicants.

“PwC’s culture and practice has distributed the benefits of its enormous success unequally – systematically favoring younger applicants at the expense of their older counterparts,” the lawsuit said.

The company did not immediately return a request for comment on Thursday.

Rabin is backed by the group AARP, which often gets involved in age bias cases. William Rivera, the group’s senior vice president for litigation, said in a statement that “there is no justification for hiring based on unfounded age stereotypes.”

Rabin is seeking to represent a class of PwC job applicants that could include thousands of people. The company has more than 46,000 U.S. employees, according to its website.

The average age of a PwC worker in 2011 was 27, according to a report the company released that year, and two-thirds of its workers were in their 20s or early 30s.

The median age of U.S. accountants and auditors is 43, according to the federal Bureau of Labor Statistics.

The number of age discrimination lawsuits filed spiked during the recession when many companies laid off workers who claimed they were targeted because of their age, and has fallen in the last few years. The issue has been a particular concern for tech companies.

Facebook Inc in 2013 agreed to settle claims by a California state agency that it violated the law by posting job ads seeking recent college graduates. Lawsuits making similar claims are pending against Google Inc and Twitter Inc.

IBM lost a bid in November to dismiss a proposed class action lawsuit claiming it lied about needing to downsize so it could replace older workers with recent graduates.

The case is Rabin v. PricewaterhouseCoopers LLP, U.S. District Court for the Northern District of California, No. 3:16-cv-02276.