Update: This offer has ended.

If you're a Prime member, you already have access to Prime Music for free, which includes about two million songs. The premium service, Music Unlimited, gives you access to 10 million songs. If you've never signed up for Music Unlimited before, you can do so now and get four months for 99 cents.

After that, you'll pay $7.99 a month if you want to keep going. That's still a discount compared to non-Prime members who have to pay $9.99 a month, and it's a better deal than Spotify Premium, which is also $10 a month.

The deal says it's for "new users," but that doesn't mean new Prime users. It's referring to new users to the Music Unlimited service itself. So if you've had Prime for a long time and just never used the music service, you can still get the discount.

This promotion is part of Amazon's lead-up to Prime Day on July 11. You can't combine it with Music Unlimited's 30-day free trial. It's either this or that, not both, and it all expires July 12.