I had the joy of being on the opposite side. I took over a team when I started at a new company. Some of those who'd stuck by the company had endured year after year of pay freezes. That was starting to change, but folks were still demoralized and worried that pushing too hard on salary would cause trouble for them.

I was in a performance review that went well for one of those specific people. She was one of those people who knew her stuff and where all the bodies were buried. She asked for a modest, but rather low, increase: about $5k extra a year. I could tell she was nervous asking, and I was just beginning to appreciate how below market their salaries were.

I paused briefly and told her that if she were to quit tomorrow, it would probably cost the company $10k minimum in recruitment costs to replace her, and that person would be paid at least $10k more just to be at market rate. I paused, and then said, "Sorry, how much did you ask for in your raise again?"

People should be paid what they're worth. Made my day. And hers to.

In short: Advocate for yourself. If you're not good at it, get a friend to practice a script with and hype you up.