Wrong (invalid) keyboard settings in user's environment

I have set my keybaord via

localectl set-x11-keymap de pc105 nodeadkeys

After each log-in in my ~/.config/xfce4/labwc/environment occurs XKB_DEFAULT_LAYOUT=de(latin1-nodeadkeys).

This seems to be invalid and in my env after login I see XKB_DEFAULT_LAYOUT=us.

Workaround:

localectl set-x11-keymap de

Possibly related: #209 (closed)