qtqr fails to decode qrcode from file

[Zaphod BIII]

Linux Mint 18 'Sarah', Cinnamon 64-bit

QtQR is able to create and save a QRCode but decode fails.
qr-tools (1.4~bzr21-1) unstable (from Synaptic Package Manager)

Run QtQR, click button Decode and select Decode from File. Select previously created .png file. Nothing happens (reproducible).

[Zaphod BIII (maheinmuc)]

/usr/bin/qtqr

Python 2.7.12 (default, Jul 1 2016, 15:12:24)
[GCC 5.4.0 20160609] on linux2
Type "copyright", "credits" or "license()" for more information.
>>>
=================== RESTART: /home/zaphod/_SDK/python/qtqr ===================
Traceback (most recent call last):
  File "/home/zaphod/python/qtqr", line 540, in decodeFile
    if qr.decode():
  File "/usr/lib/python2.7/dist-packages/qrtools.py", line 181, in decode
    raw = pil.tostring()
  File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 695, in tostring
    "Please call tobytes() instead.")
Exception: tostring() has been removed. Please call tobytes() instead.

[Zaphod BIII (maheinmuc)]

/usr/lib/python2.7/dist-packages/qrtools.py

181c181
< raw = pil.tobytes()
---
> raw = pil.tostring()

works for me.