diff --git a/addons/point_of_sale/tools/posbox/overwrite_before_init/etc/init_posbox_image.sh b/addons/point_of_sale/tools/posbox/overwrite_before_init/etc/init_posbox_image.sh
index a9dfda63070..4b29ca22e77 100755
--- a/addons/point_of_sale/tools/posbox/overwrite_before_init/etc/init_posbox_image.sh
+++ b/addons/point_of_sale/tools/posbox/overwrite_before_init/etc/init_posbox_image.sh
@@ -17,8 +17,7 @@ export DEBIAN_FRONTEND=noninteractive
 echo "nameserver 8.8.8.8" >> /etc/resolv.conf
 
 
-apt-get update
-apt-get -y dist-upgrade
+apt-get update && apt-get -y upgrade
 # Do not be too fast to upgrade to more recent firmware and kernel than 4.38
 # Firmware 4.44 seems to prevent the LED mechanism from working
 
@@ -39,6 +38,8 @@ rm -rf /usr/share/doc
 pip install pyusb==1.0.0b1
 pip install qrcode
 pip install evdev
+pip install simplejson
+pip install unittest2
 
 # --upgrade because websocket_client in wheezy is bad:
 # https://github.com/docker/compose/issues/1288
diff --git a/addons/point_of_sale/tools/posbox/posbox_download_images.sh b/addons/point_of_sale/tools/posbox/posbox_download_images.sh
index 09bd79b2103..33beddac041 100755
--- a/addons/point_of_sale/tools/posbox/posbox_download_images.sh
+++ b/addons/point_of_sale/tools/posbox/posbox_download_images.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
 
-wget 'https://downloads.raspberrypi.org/raspbian_lite_latest' -O raspbian.img.zip
+wget 'http://downloads.raspberrypi.org/raspbian_lite/images/raspbian_lite-2017-07-05/2017-07-05-raspbian-jessie-lite.zip' -O raspbian.img.zip
 unzip raspbian.img.zip
 wget 'https://github.com/dhruvvyas90/qemu-rpi-kernel/raw/master/kernel-qemu-4.4.13-jessie' -O kernel-qemu