For Silicon Valley’s “unicorns,” the writing is on the wall—literally, flyers warning of their plummeting values are appearing on walls.

On Wednesday, Quartz reporter David Yanofsky spotted paper flyers taped around Palo Alto’s University Avenue, a major artery of tech offices in the city, warning Palantir employees’ of their worthless company shares. Along with stern statements about shares of Palantir’s common stock, which are worth $0, according to the flyer’s author, is a slain unicorn, bleeding rainbow colors.

“Go on a strike or take over the company. Just don’t let your founders and investors screw you over,” read the flyers, in capital letters.

Founded in 2004, Palantir is a venture capital-funded company that provides data analysis software, and whose clients include U.S. government agencies. In December, it closed a $880 million mega-round of funding, and it’s currently valued at $20 billion. Palantir co-founder and CEO Alex Karp has also publicly voiced the company’s desire to remain private, likely another reason for the flyers’ alarm about the company’s employee stock.

Though Palantir appears to be doing just fine as a business, at least from the outside, the flyers are emblematic of a growing concern over Silicon Valley’s ballooning startup valuations and easy money. Over the past couple of years, dozens of companies have joined the coveted “unicorn” club by achieving valuations of $1 billion of more, but a chill seems to be setting over the industry. In recent times, several investors have warned of impending unicorn deaths, and a tracker for down rounds—when a company’s valuation falls when it raises new funding—has appeared online, courtesy of venture capital data company CB Insights. The case of Good Technology, which sold to BlackBerry in late 2015 for less than it was valued, leaving many employees with worthless company stock, has also precipitated the concerns.

On the upside, there’s already plenty of gear for those ready to shed some unicorn tears.