# TS2664: Invalid module name in augmentation, module '…' cannot be found.

> A declare module augmentation names a module that can't be resolved. Fix the module name or install the package being augmented.

## What it means

A `declare module "name" { ... }` inside a module file augments an existing module, so the name
has to resolve to one. Here it doesn't resolve to any file or package.

## Example

```ts
declare module "missing-lib" {
  export const extra: number;
}
export {};
```

## How to fix

- Check the module name for typos; it must match what `import` would resolve.
- Install the package (or its types) that you're augmenting.
- If you meant to declare a module that has no types, put `declare module "name"` in a `.d.ts` file that is not itself a module (no top-level `import`/`export`).

Source: https://ts-r.dev/errors/TS2664/