## `allowCheatcodes`

### Signature

```solidity
function allowCheatcodes(address account) external;
```

### Description

In forking mode, explicitly grants the given address cheatcode access.

By default, the test contract and its deployer have cheatcode access. Contracts deployed by addresses with cheatcode access also inherit it. However, contracts already deployed on the forked network do not have access.

### Parameters

| Parameter | Type      | Description                              |
|-----------|-----------|------------------------------------------|
| `account` | `address` | The address to grant cheatcode access to |

### Examples

```solidity [test/AllowCheatcodes.t.sol]
function testAllowCheatcodes() public {
    vm.createSelectFork(MAINNET_RPC_URL);
    
    // Grant cheatcode access to an existing on-chain contract
    address existingContract = 0x1234...;
    vm.allowCheatcodes(existingContract);
}
```

### Gotchas

:::note
This is only useful for complex test setups in forking mode where you need existing on-chain contracts to use cheatcodes.
:::

### Related Cheatcodes

* [`createFork`](/reference/cheatcodes/create-fork) - Create a fork
* [`createSelectFork`](/reference/cheatcodes/create-select-fork) - Create and select a fork