Hi Skyler, It's a shame that nobody had pointed out this (quite common) missing piece earlier. Skyler via Bug reports for GNU Guix writes: > In spite of being reasonable, it is not particularly intuitive. Could I recommend an addition to the manual in section "7.1 Invoking guix-shell", adding text like the below after the example invocation `guix shell python python-numpy -- python3​`? > > "Note that it is necessary to include the main python package in this command even if it is already installed into your environment. This is so that the shell environment knows to set PYTHONPATH and other related variables. The shell environment cannot check the previously installed environment, because then it would be non-deterministic." Yes, this would be a good idea. I can try to do this right now. Best, -- Josselin Poiret