Failing after images created

[mitchmalone]

Images seem to generate fine, but after they're done the task fails.

Mitch:sliceup mitch$ grunt spritesheet
Running "spritesheet:generate" (spritesheet) task
src/img/sprite.png created.
src/img/sprite@2x.png created.
Fatal error: spawn ENOENT
Mitch:sliceup mitch$

This is my configuration:

spritesheet: {
    generate: {
        sprites: {
            "src/img/sprite.png": ['src/sprites/**/*.png'],
        },
        sheet: "src/less/topme-sprite.less",
        templateUrl: "sprite-template.mustache",
        options: {
            cache: false
        }
    }
}

[mitchmalone]

Any update on this?