error and you’ve installed Nix with your system package manager: Add yourself to the nix-users group Log out and log back in This error is harmless, but you can fix it as follows: Run sudo nix-channel note that your user should be a member of the group you specify with GROUP="xxx" . Depending on your Linux distributions you may want to use a different group. To check if hdc is now working, you can run "--config", "imports_granularity=Module", "--config", "group_imports=StdExternalCrate" ] } } } } }config\" \"--libs\" \"--cflags\"