1010_bieber_launch

Justin Bieber's
getting buff!

The "As Long As You Love Me" singer must be hitting the gym pretty hard -- the Biebs is finally starting to bulk up a little.

Justin showed off his chest and arms (yet again) on Wednesday, posting a shirtless picture with his personal trainer on Instagram.

The 19-year-old has always been in shape, but it looks like he's got a little more meat on his arms now. We gotta say, it's a nice improvement!

What do you think of Justin's shirtless selfie? Tell toofab in the comment section below, and click "Launch Gallery" above to see more shirtless stars!