# Fix macOS PHP NSCFConstantString Fork Error with One Env Var

*Originally published at [recca0120.github.io](https://recca0120.github.io/en/2022/12/26/php-objc86150-nscfconstantstring-initialize-may-have-been-in-progress-in-another-thread/)*

When using Guzzle Client in `artisan tinker`, macOS throws `objc[86150]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called`. This is caused by the Objective-C runtime's safety check during fork.

## Disable the Fork Safety Check

Set an environment variable to skip the check:

```bash
export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES
```

Add it to `~/.bashrc` or `~/.zshrc` so you don't have to set it manually every time.