Justin Bieber may be getting boxing lessons from Mike Tyson, but it looks like the Pop star might need to spend his free time learning how to defend himself against glass walls instead.

According to TMZ, the 18-year-old singer was “knocked out cold” after he walked into a glass wall backstage during a concert in Paris:

We just spoke with Justin, who said he was performing on stage, and in between songs he walked backstage and hit the glass. He says he was disoriented, but went back on stage and finished his set.

As he walked to his dressing room he passed out cold, for around 15 seconds. Doctors say Justin suffered a concussion but he’ll be ok.

This isn’t the first (or second) time Justin Bieber has gone to war with a solid block of glass, and lost.

In 2010, back when he was still wearing that weird comb-over bowl haircut, the Biebz was playing around with a set of revolving doors when he lost his footing and rammed his head into the glass panel ahead of him.

Then there’s this:

After his latest run-in with a glass panel, Justin told TMZ, “I guess me and glass windows just don’t work.”

Uhh … no sh*t, Sherlock.

Glass Walls: 3 / Justin Bieber: 0