Error while casting as decimal with precise value

I'm trying to cast a quantity attribute in my Laravel model as a decimal with three decimal places. I have successfully used float and double casts, but I need more precise control over the decimal points. Can you help me set this up? Casts doesn't work with decimal:3. This is the same datatype I am using in mysql db.

class ProductionOrder extends Model
{
    use HasFactory, HasUuids;

    protected $table = 'production_orders';
    protected $primaryKey = 'po_id';
    public $incrementing = false;
    protected $keyType = 'string';

    protected $fillable = [
        'po_number',
        'material_id',
        'quantity',
        'status',
        'record_date',
        'created_by',
        'updated_by',
    ];

    protected $casts = [
       //'quantity' => 'double',  <----- this works
       'quantity' => 'decimal:3',       //this doesn't
    ];

I am using laravel 10 on php 8.2