---
title: "Announcing Rust 1.99.1"
slug: announcing-rust-1-99-1
url: https://listedarticles.com/articles/announcing-rust-1-99-1
canonical_url: https://blog.rust-lang.org/2026/10/15/Rust-1.99.1/
content_type: changelog
language: en
published_at: 2026-10-15T00:00:00.000Z
updated_at: 2026-10-16T02:13:14.528Z
author: "The Rust Team"
authored_by: human
publisher: "Rust Blog"
publisher_url: https://blog.rust-lang.org/
topics: ["Rust", "Programming Languages", "Open Source"]
license: all-rights-reserved
word_count: 321
reading_minutes: 1
citation: "The Rust Team, Rust Blog. \"Announcing Rust 1.99.1.\" 15 Oct 2026. https://blog.rust-lang.org/2026/10/15/Rust-1.99.1/ (all-rights-reserved)"
# The full text follows. The web page shows an extract and sends readers
# to the source above; quote the citation and link the canonical URL.
---

# Announcing Rust 1.99.1

> The Rust team released 1.99.1, a point release fixing regressions from 1.99.0. The post lists the notable fixes and points users at rustup update as the upgrade path.

The Rust team has published a new point release of Rust, 1.99.1. Rust is a programming language that is empowering everyone to build reliable and efficient software.

If you have a previous version of Rust installed via rustup, getting Rust 1.99.1 is as easy as:

```
rustup update stable
```

If you don't have it already, you can [get `rustup`](https://www.rust-lang.org/install.html) from the appropriate page on our website.

## What's in 1.99.1

Rust 1.99.1 fixes the following regressions from prior releases:

- [Missing symbol `wcslen`](https://github.com/rust-lang/rust/issues/163614): Some Rust targets were getting link errors for missing `wcslen`, and that function is now present in Rust's compiler-builtins library as a fallback.

  The LLVM `loop-idiom-wcslen` pass may introduce calls to `wcslen` as an optimization, and some Rust targets did not have that function readily available in `libc` or elsewhere. The UEFI targets in particular were broken for any project using `std`, as some of these calls were introduced in the precompiled standard library, but the issue was also reproducible for similar user code patterns.
- [Miscompilation of FFI `bool` return values on x86\_64](https://github.com/rust-lang/rust/issues/163911): Rust functions returning `bool` through FFI could leave bits 1-7 of the return register unspecified, causing callers to observe raw values other than `0` or `1`. This return type is now marked for zero-extension again, as required by the ABI.
- [`rust-lld` failed to load `libLLVM` on macOS](https://github.com/rust-lang/rust/issues/163947): This linker could fail to run if the compiler was invoked without the `rustup` proxy, as there was no direct setting for the appropriate library search path. Now `rust-lld` is built with an `rpath` entry for the directory containing `libLLVM.dylib`.

If you'd like to help us out by testing future releases, you might consider using the beta (`rustup default beta`) and nightly (`rustup default nightly`) channels locally and in your CI. Please [report](https://github.com/rust-lang/rust/issues/new/choose) any bugs you might come across!

### Contributors to 1.99.1

Many people came together to create Rust 1.99.1. We couldn't have done it without all of you. [Thanks!](https://thanks.rust-lang.org/rust/1.99.1/)