Hi Guix, After some discussion in IRC and testing, I found out that adding $GUIX_PROFILE/share/fonts to the webkit sandbox (during initialization via `webkit_web_context_add_path_to_sandbox') resolves this problem. A more general solution would be to iterate over $XDG_DATA_DIRS, append `/fonts' to each item and add the resulting path to the sandbox (if it is a directory). As this is a problem related to the webkit sandbox, it probably affects other packages, that make use of it, as well. Looking even deeper (i.e. diving into the webkitgtk source), it appears that there is indeed a `bindFonts' procedure in the BubblewrapLauncher, but that only considers $XDG_DATA_HOME/fonts, not all of $XDG_DATA_DIRS. As this is the root of the issue, it should probably be fixed there. Regards, Leo Note for those looking for a workaround: Assuming you're installing your fonts to $GUIX_PROFILE/share/fonts, making $XDG_CACHE_HOME/fonts or $HOME/.fonts a symlink to that should work.