gistfile1.txt

diff --git a/.envrc b/.envrc
index 8aaa78e..1d47631 100644
--- a/.envrc
+++ b/.envrc
@@ -7,6 +7,17 @@ watch_dir nix
 watch_file default.nix BUILD.nix
 
 # Build and load the devshell
-out=$(nix-build -A shell --no-out-link)
+layout_dir=$(direnv_layout_dir)
+[[ -d "$layout_dir" ]] || mkdir -p "$layout_dir"
+if [[ ! -f "$layout_dir/last-build"
+   || "$layout_dir/last-build" -ot BUILD.nix
+   || "$layout_dir/last-build" -ot default.nix
+   || "$layout_dir/last-build" -ot nix/sources.json
+   || "$layout_dir/last-build" -ot nix/sources.nix
+   || "$layout_dir/last-build" -ot nix/default.nix
+   ]]; then
+  nix-build --builders '' -A shell --out-link "$layout_dir/shell"
+  touch "$layout_dir/last-build"
+fi
 # shellcheck disable=SC1091
-source "$out/env.bash"
+source "$layout_dir/shell/env.bash"