[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Assert](https://evolu.dev/docs/api-reference/common/Assert) › assertFalse

```ts
const assertFalse: (value: unknown) => asserts value is false;
```

Defined in: [packages/common/src/Assert.ts:220](https://github.com/evoluhq/evolu/blob/ecbac001e0c18bbc45b44715f49ecc3a768c5ec9/packages/common/src/Assert.ts#L220)

Asserts that a value is exactly `false` and narrows it to `false`.

Unlike [assert](https://evolu.dev/docs/api-reference/common/Assert/variables/assert), this checks an exact boolean value instead of falsiness
and does not require a custom message.

### Example

```ts

const value: unknown = false;
assertFalse(value);
assertType<typeof value, false>();
```