It is against the law for employers to discriminate against employees based on their age. However, technology companies may be engaging in age bias in some not-so-subtle ways by trying to phase out older workers for younger, cheaper ones.

While the average age of U.S. employees is 42, workers in Silicon Valley are an average of 31 years old or younger, according to PayScale. For example, the median age of employees is 28 at Facebook, 30 at Google and 29 at LinkedIn.

A common excuse for phasing out of older employees is that they are unable to keep up with the fast-changing world of technology. Employers assume younger workers are more likely to know about the industry’s latest developments. In a comment to the New York Times, HubSpot CEO Brian Halligan once said that his software company was “trying to build a culture specifically to attract and retain Gen Y’ers.” He claimed that, “in the tech world, gray hair and experience are really overrated.”

Between 2008 and 2015, 226 age discrimination complaints, involving 150 of Silicon Valley’s largest companies, were filed with the California Department of Fair Employment and Housing. They exceeded the number of racial discrimination complaints by 28 percent.

Several recent lawsuits indicate employees are no longer willing to tolerate age discrimination in the workplace. In August, former HP employees sued the company for allegedly targeting workers aged 40 and older in large-scale layoffs and replacing them with younger employees. Google is also facing a lawsuit for age bias in the hiring process.

Although many in the tech industry may view making employment decisions based on age as commonplace, age discrimination is illegal. It is important for people who have experienced age discrimination to speak up about it and fight for their right to fair employment opportunities.