Eloquent and mysql casting to boolean not working

  $mm = new MyModel();
  $mm->share_info = 'yes';
  $mm->save();

model:

class MyModel extends Model
{

    public $table = 'mymodel';

    const CREATED_AT = 'created_at';
    const UPDATED_AT = 'updated_at';



    public $fillable = [
        'share_info',
    ];


    protected $casts = [
        'share_info' => 'boolean',
    ];

result column, is boolean tinyint in mysql.

Result is 0 in DB instead of 1.

Why?

  $mm->share_info = true;

does work as expected

via Toskan