What's a good way to gain more mass in your arms?

I’m a 21 year old male, and I’ve been working out and dieting recently, and I’d have to say I’ve shed quite a few pounds. Howeverrr, with the fat that I’ve lost, my arms look unproportionally scrawnier than the rest of my body. Even after I lift weights, my arms just look more toned; they don’t actually look bigger. Does anyone of a good way for me to gain muscle mass in my arms?