# Viewport `meta` tags should not be used in `_document.js`'s ``
#### Why This Error Occurred
Adding `` in `pages/_document.js` will lead to unexpected results since it cannot be deduped.
The viewport tag should be handled by `next/head` in `pages/_app.js`.
#### Possible Ways to Fix It
Set your viewport `meta` tag in `pages/_app.js` instead:
```tsx
// pages/_app.js
import Head from 'next/head'
function MyApp({ Component, pageProps }) {
return (
<>
)
}
export default MyApp
```
### Useful Links
- [Issue #13230](https://github.com/vercel/next.js/issues/13230), which led to the creation of this warning.