diff --git a/scripts/mk_all.sh b/scripts/mk_all.sh
index 8d4c3cdebf309..b9679e7211308 100755
--- a/scripts/mk_all.sh
+++ b/scripts/mk_all.sh
@@ -4,17 +4,23 @@
 # Examples:
 #   ./scripts/mk_all.sh
 #   ./scripts/mk_all.sh data/real
+#   ./scripts/mk_all.sh ../archive
 #
 # Makes a mathlib/src/$directory/all.lean importing all files inside $directory.
 # If $directory is omitted, creates `mathlib/src/all.lean`.
 
 cd "$( dirname "${BASH_SOURCE[0]}" )"/../src
 if [[ $# = 1 ]]; then
-  dir="$1"
+  dir="${1%/}"  # remove trailing slash if present
 else
   dir="."
 fi
 
+# remove an initial `./`
+# replace an initial `../test/` with just `.` (similarly for `roadmap`/`archive`/...)
+# replace all `/` with `.`
+# strip the `.lean` suffix
+# prepend `import `
 find "$dir" -name \*.lean -not -name all.lean \
-  | sed 's,^\./,,;s,\.lean$,,;s,/,.,g;s,^,import ,' \
+  | sed 's,^\./,,;s,^\.\./[^/]*,,;s,/,.,g;s,\.lean$,,;s,^,import ,' \
   | sort >"$dir"/all.lean