(WTVO) — Beware, millennials! Thanks to the Age Discrimination in Employment Act of 1967, dismissing an over-40 co-worker with an “Ok, Boomer” insult could get you fired.

Millennials have taken to using the “Ok, Boomer” line to be dismissive of criticisms from the Baby Boomer generation (1946-1964), which has become “the rallying cry for millions of fed up kids,” according to journalist Taylor Lorenz.

But the Age Discrimination in Employment Act prohibits discrimination against people 40 and over.

Use of the phrase could be considered to create a “hostile work environment,” according to Inc., which constitutes “behavior that violates the law-such as age, race, or sex discrimination.”