# OCaml 5.5.1 — OCaml 5.5.1

- Product: OCaml (https://whatsnew.fyi/product/ocaml)
- Vendor: OCaml
- Date: 2026-09-04
- Version: 5.5.1
- Original notes: https://github.com/ocaml/ocaml/releases/tag/5.5.1
- Permalink: https://whatsnew.fyi/product/ocaml/releases/5.5.1

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** — Type system bug fix for module-dependent functions
- **security** — Fix overflow in Marshal
- **security** — Fix overflow in bytecode loading
- **fixed** — Various runtime fixes
- **fixed** — Restore cloning support on macOS

- Type system bug fix for module-dependent functions
- Security fix: overflow in Marshal
- Security fix: overflow in bytecode loading
- Various runtime fixes
- Restore cloning support on macOS 

See [detailed list of changes](https://github.com/ocaml/ocaml/blob/5.5/Changes#7).