This patent specification describes a barcode-reading enhancement accessory for a mobile device having a barcode-reading capability. The accessory may include an outer case and an inner carriage. A mobile device is encased in the inner carriage, and the combination of the inner carriage and the mobile device may be accommodated in the outer case. The inner carriage is configured to accommodate a mobile device of a particular size such that a mobile device of a different size may be accommodated in the outer case using a different inner carriage. The accessory may also include an optic system to fold an optical path of a field of illumination of a light source of the mobile device and/or a field of view of a camera of the mobile device.