Prevent upscale of images

Hi, I would like an option for either presets or thumbs in general, that prevent upscaling of images.

    'thumbs' => [
        'upscale' => false,
        'presets' => [
            'maxSize' => ['width' => 2400, 'height' => 2400, 'crop' => false, 'upscale' => false]
        ]
    ]

Stupid me. images are not upscaled!