Rear hub squeaking
 

Hey guys, my rear hub squeaks, but only when the wheel is being spun in the 'free' direction. I just noticed while cleaning my chain/hub this morning, the faster I spin the wheel the louder it gets, any ideas?

I'm somewhat (very) rough on my bike, so I'm guessing the bearings either need a re-grease or a replace but best guesses would be welcome.