---
title: "defineMimeType"
source: "https://github.com/remix-run/remix/blob/8905f3943706e1f53696ab83e70a84873cabfc90/packages/mime/src/lib/define-mime-type.ts#L51"
---

# defineMimeType

## Summary

Registers a custom MIME type for one or more file extensions.

Use this to add support for file extensions not included in the defaults,
or to override the behavior of existing extensions.

## Signature

```ts
function defineMimeType(definition: MimeTypeDefinition): void

```

## Example

```ts
defineMimeType({
  extensions: ['x-myformat'],
  mimeType: 'application/x-myformat',
})

```

## Parameters

### `definition`

The MIME type definition to register