libX11 not found after binary install of Guix

[Marco van Hulten <marco@hulten.org>]

Hi all—

On a freshly installed Ubuntu 18.04 I installed Guix following the
instructions on, except for the fact that I did it from grml in a
chroot(8)ed environment

    https://www.gnu.org/software/guix/manual/en/html_node/Binary-Installation.html

Rebooting into Ubuntu I was happy to find that guix-daemon was running.
Then I tried install something:

$ guix package -i hello
/gnu/store/q19l04vd2za80mk1845pz7r8cz29qk43-bash-minimal-4.4.23/bin/bash: error while loading shared libraries: libX11.so.6: cannot open shared object file: No such file or directory

At least on the host system it exists:

$ ls -l $(locate libX11.so.6)
lrwxrwxrwx 1 root root      15 Aug 29 20:18 /usr/lib/x86_64-linux-gnu/libX11.so.6 -> libX11.so.6.3.0
-rw-r--r-- 1 root root 1277384 Aug 29 20:18 /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0
$ file /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0
/usr/lib/x86_64-linux-gnu/libX11.so.6.3.0: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=46d02d32191b5470a70bf6710997bf89b8b8ae38, stripped

but it is not in the Store:

$ ls -d /gnu/store/*libx11*
ls: cannot access '/gnu/store/*libx11*': No such file or directory

Should it be there?

What could've gone wrong?

—Marco