PHP Strict Warning: Passing by reference

I'm getting the following PHP warning:

Strict warning: Only variables should be passed by reference in yelp_api_replace_token() (line 22 of yelp_api.tokens.inc).

Apparently PHP does not like the way that array_shift is used in the following line:
$type = trim(str_replace('[', '', array_shift(explode(':', $token))));

I added an @ to quiet the warnings on my system, but the line should probably be rewritten. For now, here's the modified line:

$type = trim(str_replace('[', '', @array_shift(explode(':', $token))));