---
synopsis: "`builtins.nixVersion` now returns a fixed value \"2.18.3-lix\""
cls: 558
credits: jade
category: Breaking Changes
---

`builtins.nixVersion` now returns a fixed value `"2.18.3-lix"`. This prevents
feature detection assuming that features that exist in Nix post-Lix-branch-off
might exist, even though the Lix version is greater than the Nix version.

In the future, check for builtins for feature detection. If a feature cannot be
detected by *those* means, please file a Lix bug.