Everyone has seen Home Alone, and with Christmas on the way – or just upon us according to the shops who all have cards and decorations out – meaning the Macaulay Culkin classic is set to be rehashed again.

In case you’ve been under a rock and not seen the film, Kevin McCallister is left home alone, and has to defend his house from two burglars, who aren’t the smartest cookies in the jar.

One thing about the film that has always had people scratching their heads is the fact that Kevin orders pizza, just after his phone lines are destroyed by a tree falling on them during a storm, meaning he can’t contact his parents.

Luckily for us, after years of wondering, one fan has a simple answer as to why that happens, and it’s petty ingenious.

The Reddit user claimed:

I always assumed the tree actually severed the main trunk line to the whole town, but local calls within the same exchange still worked.

It turns out he was right, after Huffington Post spoke to Hank Hultquist, AT&T’s Vice President for Federal Regulatory Affairs:

Everything is changing now because of all this phone capability is moving into the cloud, but in 1990, that was absolutely a plausible scenario.

When you’re trying to call from Paris, now you’re relying on a whole series of connections including undersea cables, any one of which could have a problem, which would prevent you from reaching some particular telephone number.

So simple, but amazing.