How can I enable php fileinfo() on Forge?

Hi,

I am using this for Image manipulation

http://glide.thephpleague.com/

On my local machine all is running well, but on my Server (via Forge), the images are not created in the correct size.

I assume that I need to enable php fileinfo() via Forgen, but I have no idea how to do that. Normally this extension should be enabled in php.ini, but I cannot find this commented entry.

Thanks

kay899