Failing to Install Plex

So I have CentOS 7 64-bit with all the recent updates installed but when I attempt to install Plex I get the following error:

warning: plexmediaserver-1.1.3.2700-6f64a8d.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 3adca79d: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...
   1:plexmediaserver-1.1.3.2700-6f64a8################################# [100%]
Created symlink from /etc/systemd/system/multi-user.target.wants/plexmediaserver.service to /usr/lib/systemd/system/plexmediaserver.service.
/usr/lib/plexmediaserver/MigratePlexServerConfig.sh: line 161: [: !=: unary operator expected
[root@mediaserver tmp]#

What's wrong? How can I fix?