# Different struct @alignOf result from 0.16 to 0.17

**URL:** <https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957>\
**Category:** Explain\
**Created:** [October 14, 2026, 6:40am UTC](https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957 "2026-10-14T06:40:24Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Travis](https://ziggit.dev/letter_avatar_proxy/v4/letter/t/bbce88/32.png) [@Travis](https://ziggit.dev/u/Travis)\
**Post date:** [October 14, 2026, 6:40am UTC](https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957/1 "2026-10-14T06:40:24Z")

</div>

This test passes with 0.16 but fails with 0.17.

```zig
test {
    const S = struct { a: [*]const u8 };
    try testing.expectEqual(8, @sizeOf(S));
    try testing.expectEqual(8, @alignOf(S)); // fails here with 0.17
}

const std = @import("std");
const testing = std.testing;

```

```console
$ zig version
0.17.0
$ zig test /tmp/tmp.zig
expected 8, found 4
...

```

Anyone know where we can learn about this @alignOf change? I’ve read throught the 0.17 release notes and searched them for ‘align’ but none of the 12 occurrences mention any changes to the @alignOf builtin.

---

<div class="post-metadata">

**Author:** ![vulpesx](https://ziggit.dev/user_avatar/ziggit.dev/vulpesx/32/3989_2.png) [@vulpesx](https://ziggit.dev/u/vulpesx)\
**Post date:** [October 14, 2026, 6:49am UTC](https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957/2 "2026-10-14T06:49:47Z")

</div>

I can’t reproduce this #worksonmymachine

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<div class="post-metadata">

**Author:** ![Travis](https://ziggit.dev/letter_avatar_proxy/v4/letter/t/bbce88/32.png) [@Travis](https://ziggit.dev/u/Travis)\
**Post date:** [October 14, 2026, 6:57am UTC](https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957/3 "2026-10-14T06:57:59Z")

</div>

Thanks! Hmm thats Wierd. I wonder what could be causing this. The only thing I can think of that I also changed today was I installed glibc-devel.i686 on this machine because I thought it was a solution to a translate-c issue i was having. 🤔

EDIT:

I mean it seems like it thinks my machine is 32 bit.

---

<div class="post-metadata">

**Author:** ![Travis](https://ziggit.dev/letter_avatar_proxy/v4/letter/t/bbce88/32.png) [@Travis](https://ziggit.dev/u/Travis)\
**Post date:** [October 14, 2026, 7:09am UTC](https://ziggit.dev/t/different-struct-alignof-result-from-0-16-to-0-17/17957/4 "2026-10-14T07:09:08Z")

</div>

I found the issue. Zigup installed a 32 bit version of 0.17 for some reason.

EDIT:

Because I accidentally installed a 32 bit version of zigup 😂. And the translate-c issue i mentioned was also a result of the 32 bit zig version.