It's not X days, it's 5 minutes... (In principle, this question belongs on meta.SO, but I think it's worth having an answer here that doesn't require people to go looking over there.) As far as I can tell, [this answer of Jeff's][1] (one of the SO founders, though no longer part of the company) is still the official reason: they don't want people to downvote a post to make it look bad, post their own answer (which will look better because it's not -1), then later take the downvote away. There are a [number][2] of [questions][3] about [this][4] on meta.SO, but despite some good arguments against locking votes after 5 minutes, SO Inc. thinks it's fine the way it is, so it's not going to change. There is a laborious workaround: edit the post then change your vote. But that only works if you have enough rep to edit w/out your edit being reviewed. So basically, don't worry about it. Since Iain's answer is the only one with a downvote, it's obvious that that's the vote you'd like to change. But it's just one downvote and since he gave an answer you'd ruled out your downvote it arguably appropriate and - unlike some SE sites - I don't think SF has people who go nuts about every single downvote. TL;DR: Don't worry about it, just move on. [1]: https://meta.stackexchange.com/a/18046/130540 [2]: https://meta.stackexchange.com/questions/80762/why-do-votes-get-locked [3]: https://meta.stackexchange.com/questions/6250/vote-too-old-to-be-changed-unless-post-is-edited [4]: https://meta.stackexchange.com/questions/94567/you-last-voted-on-this-answer-6-mins-ago-locked-too-short