# TS1121: Octal literals are not allowed. Use the syntax '…'.

> A number starts with `0` followed by digits, the legacy octal form. Write `0o` for octal, or drop the leading zero for decimal.

## What it means

Numbers like `0755` were octal in old JavaScript. They're not allowed in strict mode or in
TypeScript. The message suggests the `0o` form with the same value.

## Example

```ts
const mode = 0755;
export {};
```

## How to fix

- For an octal value, use the `0o` prefix: `0o755`.
- For a decimal value, remove the leading zero: `755`.

Source: https://ts-r.dev/errors/TS1121/