Fans of iconic psychedelic rockers Pink Floyd can now stream the band's entire discography for free on Spotify (and Spotify only), thanks to a promotional campaign between Pink Floyd and the music streaming service.

The deal was that as soon as Floyd's well-known song "Wish You Were Here" hit 1 million streams, starting on Friday June 14th, the band's discography would be "unlocked" by Spotify, making it available for free to the service's 20 million registered worldwide users. The campaign took less than four days to complete.

That doesn't mean, however, that Pink Floyd's music is a newcomer to streaming; as the Guardian notes, subscribers to Rhapsody, Deezer and/or Rdio have been able to listen to Dark Side of the Moon -- still the record-holder for most weeks spent on the Billboard 200 (well over 800 weeks) and a constant presence on the Billboard 200 and/or Catalog Albums charts from 1973-1988 and 1991-present -- to their hearts content for years now.

You can listen to Dark Side of the Moon below, or click here to browse the band's entire catalog on Spotify.