User (uid) PHP validator (with relationship) is splitting the $argument into single digits

Have a view set up to take an argument from user/%/linked-students. It worked during my first testings, then just stopped all the sudden, and I've finally figured out why.

Validation PHP code:

global $user;
return $argument[0] == $user->uid;

I was testing on the path user/14/linked-students, and started looking at the argument with drupal_set_message. Turns out that $argument[0] has a value of "1", which was odd, since it should have been "14". Thought it had something to do with the fact that I was logged in with my admin user too.

Anyhow, but then $argument[1] turns out to be "4". So it's looking like the $argument array is for some reason an array of each digit in the actual argument. This was why it was working when I started testing, since I was working with single-digit users.

Anyhow, no idea why this might be, but using arg(1) instead of $argument[0] seems to do the trick for now.

Not sure if it's important, but my user:uid argument was set up to use a node reference relationship. Not sure if this is universal with the $argument array, but it might lead to loads of wasted time for many, so I'm marking as critical :)

Cheers all!