The special offer Microsoft announced at E3 where people who buy Fallout 4 on Xbox One get a free copy of Fallout 3 doesn’t last forever. Microsoft has now revealed that you’ll need to buy Fallout 4 on Xbox One by February 6, 2016 to get a free backwards-compatible version of Fallout 3 for Xbox 360.

On the Xbox.com site, the language says this offer is good “for a limited time.” But Fallout 4’s product page on the actual Xbox One games store includes mention of the end-date. The code for Fallout 3 will be delivered to you by way of a message 7-10 days after your purchase.

We’ve also now learned that Fallout 3 will be among the 100-plus Xbox 360 titles available on Xbox One through backwards compatibility when the feature arrives as part of the New Xbox One Experience on November 12. The full list of supported titles will be revealed on November 9.

Microsoft also worked with Fallout developer Bethesda on a special-edition Xbox One console that comes with a 1 TB system and a copy of the game (plus Fallout 3) for $399.

Fallout 4 launches on November 10 for PC, Xbox One, and PlayStation 4. We’ll have more coverage of the game this coming Monday, November 9. For now, you can check out this artist’s rendering of Disney princesses in the world of Fallout.