My roommate uses my stuff without asking… and acts like it’s normal

I live with a roommate, and overall things are okay… but one thing is really starting to bother me. They keep using my stuff without asking. At first it was small things — like snacks, chargers, random items. I ignored it because I didn’t want to make a big deal out of it. But now it’s become a pattern. I’ll notice things missing or used, and when I ask, they just say it casually like “oh yeah I used it, hope that’s fine.” No apology, no asking before… just assuming. And the problem is, if I suddenly say something now, it might come across like I’m overreacting because I didn’t speak up earlier. But at the same time, it’s starting to feel disrespectful. I don’t know if I should confront it directly or just start setting boundaries quietly. Has anyone dealt with something like this?