# Crystal 1.19.1

- Product: Crystal (https://whatsnew.fyi/product/crystal)
- Vendor: Crystal Language
- Date: 2026-01-20
- Version: 1.19.1
- Original notes: https://github.com/crystal-lang/crystal/releases/tag/1.19.1
- Permalink: https://whatsnew.fyi/product/crystal/releases/1.19.1

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **fixed** — Fix kqueue timer duration calculation in concurrency
- **fixed** — Fix time calculations in IOCP and Monitor thread in concurrency

###### Bugfixes

###### stdlib

- _(concurrency)_ **[regression]** Fix kqueue timer duration calculation ([#16581], thanks @skuznetsov)
- _(concurrency)_ **[regression]** time calculations in IOCP and Monitor thread ([#16583], thanks @ysbaddaden)

[#16581]: https://github.com/crystal-lang/crystal/pull/16581
[#16583]: https://github.com/crystal-lang/crystal/pull/16583

###### Infrastructure

- Changelog for 1.19.1 ([#16590], thanks @ysbaddaden)

[#16590]: https://github.com/crystal-lang/crystal/pull/16589