qt5 installation

I'm running a stable branch of Slackware 14.2 and trying to install qt5 from SlackBuilds (I need it as a dependence for another package), got the following output:

Code:root@neuland:/usr/local/qt5# ./qt5.SlackBuild

SlackBuild Options:

CCACHE: no
DOCS: no
EXAMPLES: no
PROPRIETARY_CODECS: no
PULSEAUDIO: yes
WEBENGINE: yes
LDGOLD: no

Removing any existing source directory. Please wait...
tar: This does not look like a tar archive
xz: (stdin): File format not recognized
tar: Child returned status 1
tar: Error is not recoverable: exiting nowWhat should I do?