Yovanna Ventura justin bieber studio model hollywood smile

We love the fact that Madison Beer is always such a sweetheart when we snap her photo!

On Tuesday night the 15-year-old singer joined mentor Justin Bieber at the recording studio in Los Angeles, and while it looks like he pulled an all-nighter, she checked out around 2am.

Madison and the Biebs have been working together for a while now, and the last time we caught up with her she confirmed that the two did a duet and Bieber even wrote a pair of tunes for her. But before tweeting, "music music music ... it's crazy how creative some people are it's so inspiring," Miss Madison wrote, "I love your voice and I love your smile and I think about you way too much." If it's not about the Biebs, who is it about?!

While Bieber has been hanging out with lots of young and hot single ladies lately, he took to his Instagram last night to seemingly shoot down reports that he's dating Kylie Jenner ... or model Yovanna Ventura. Biebs posted a photo of himself with Floyd Mayweather's 13-year-old daughter Iyanna and wrote, "I guess everyone I get photo'd with is automatically my girlfriend. This is my only gf @moneyyaya :p .. Had fun at the fight lil one see u soon!"

And seeing as Selena Gomez hung out with Madison and the Biebs last month in Miami, it's pretty safe to assume that he wouldn't try anything with his young protege, right?