Twitter has become the latest Silicon Valley player to be hit with a lawsuit for alleged gender discrimination.

Former employee Tina Huang has filed the class action lawsuit in California Superior Court, alleging that Twitter’s hiring and promotional practices promote a culture where women are unfairly underrepresented in the process. Huang claims that when she brought up her concerns to the Twitter higher-ups, she was immediately put on leave.

Huang’s main complaint is that Twitter’s “ladder” for advancement is a flawed system that breeds gender discrimination. For example, Twitter employees are often notified of a promotion by a “tap on the shoulder,” according to the court documents. There is apparently no clearly-stated promotion criteria or application.

“Promotion into Twitter’s senior technical positions is based on subjective judgments, by committees that are comprised of and dependent on upper management at Twitter, and predominantly male. These judgments are tainted with conscious or unconscious prejudices and gender-based stereotypes, which explains why so few women employees at Twitter advance to senior and leadership positions,” says the lawsuit in text obtained by Mashable.

Huang included a list of all the practices she alleges prevent proper gender representation in Twitter’s “ladder” process, including things like ” reliance upon subjective, gender-based and/or arbitrary criteria utilized by a nearly all male managerial workforce in making promotion decisions” and “effectively discouraging women from seeking or applying for senior level and leadership positions.”

Twitter provided a statement on the claims, saying that Huang left the company on her own accord and that “Twitter is deeply committed to a diverse and supportive workplace, and we believe the facts will show Ms. Huang was treated fairly.”

Twitter’s latest transparency report revealed that the company is 70 percent male. If you look at purely tech roles, Twitter is 90 percent male. Looking at leadership positions, Twitter checks in at 79 percent male.

Last week, a former employee sued Facebook claiming she was discriminated against based on her sex, ethnicity, and country or origin – and subsequently fired without just cause.