# How to depend on files with unrecognized by zig build system mime\_types?

**URL:** <https://ziggit.dev/t/how-to-depend-on-files-with-unrecognized-by-zig-build-system-mime-types/17973>\
**Category:** Help\
**Tags:** package-management, build-system\
**Created:** [October 15, 2026, 9:17am UTC](https://ziggit.dev/t/how-to-depend-on-files-with-unrecognized-by-zig-build-system-mime-types/17973 "2026-10-15T09:17:55Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![AndrewKraevskii](https://ziggit.dev/user_avatar/ziggit.dev/andrewkraevskii/32/2564_2.png) [@AndrewKraevskii](https://ziggit.dev/u/AndrewKraevskii)\
**Post date:** [October 15, 2026, 9:17am UTC](https://ziggit.dev/t/how-to-depend-on-files-with-unrecognized-by-zig-build-system-mime-types/17973/1 "2026-10-15T09:17:55Z")

</div>

I want to write a parser for [ifc file format](https://en.wikipedia.org/wiki/Industry_Foundation_Classes) to do some processing on them. Since its specification is published in [EXPRESS (data modeling language) - Wikipedia](https://en.wikipedia.org/wiki/EXPRESS_(data_modeling_language)) I would write a parser for express which then generates parser for ifc. To not bundle giant file into repository I want to fetch its schema with package manager. Sadly doing this will produce:

```sh
./build.zig.zon:7:20: error: unrecognized 'Content-Type' header: 'application/express'
            .url = "https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/IFC4X3_ADD2.exp",
                   ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

```

As a temporary solution I can download zip they also publish which includes this exp file. But its not a great solution considering this zip file is 150 times larger. Adding this mime type to the compiler doesn’t seem to be an option since its an open set of types. Maybe compiler should fallback to downloading as plain text if it doesn’t recognize file format?

---

<div class="post-metadata">

**Author:** ![AndrewKraevskii](https://ziggit.dev/user_avatar/ziggit.dev/andrewkraevskii/32/2564_2.png) [@AndrewKraevskii](https://ziggit.dev/u/AndrewKraevskii)\
**Post date:** [October 15, 2026, 9:21am UTC](https://ziggit.dev/t/how-to-depend-on-files-with-unrecognized-by-zig-build-system-mime-types/17973/2 "2026-10-15T09:21:36Z")

</div>

Okey i think i found answer to my question [https://codeberg.org/ziglang/zig/issues/32041](https://codeberg.org/ziglang/zig/issues/32041)