Making t-shirt sleeves more fitted?

The sleeves on some of my nicest t-shirts really flare out and I hate the way they look. Other forums suggested pinning them together to make the sleeve smaller but it seems a bid fiddly and unreliable, I can imagine the pin isn't too sturdy and most of all, it's visible. I sometimes just slightly fold the sleeve up a little but they often unravel themselves and on some t-shirts, the sleeves are too short to roll up without making them look like they're right up my arm pit.

Anybody got any cool little tips or tricks for making t-shirt sleeves more fitted (except for buying a size smaller because I want to do it to a few existing ones).

Thanks for any help!

Ive never tried it but mabye you can snip a line down the sleeve, overlap the sides and stich back together? Maybe a bit too diy/messy looking but thats the first thing that pops to mind.

Hmm, I might try this. I'd just be worried about the stitching coming loose then ending up with flaps of fabric hanging out from my armpit lol.

Do you guys know roughly what a tailor would charge for this kind of thing?

I have the same problem with some of my t-shirts
With regards to solving the problem i think the best solution would be to perhaps take them to a tailor as suggested if not sort them out yourself if you're good at sewing...

Probably about £5 a top.

I've actually just tried safety pins, thought I may as well try and they work great!

I folded the armpit seem in on itself about an inch inwards then folded it against the rest of the sleeve and held it together with a safety pin, making sure that the "lock" on the pin is on the inside of the t-shirt, away from view. Looks tons better, feels a lot more durable than I thought it'd be and even if I hold my arms up, it's not really visible and the "fold" I made could pass of as just some unusual seem.

Get bigger arms.