diff --git a/packages/hachis/hachis.20240918/opam b/packages/hachis/hachis.20240918/opam
new file mode 100644
index 00000000000..681bb177f0f
--- /dev/null
+++ b/packages/hachis/hachis.20240918/opam
@@ -0,0 +1,38 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis: "Hash sets and hash maps"
+maintainer: ["François Pottier <francois.pottier@inria.fr>"]
+authors: ["François Pottier"]
+license: "LGPL-2.0-only WITH OCaml-LGPL-linking-exception"
+homepage: "https://github.com/fpottier/hachis/"
+bug-reports: "https://github.com/fpottier/hachis/issues"
+depends: [
+  "dune" {>= "3.11"}
+  "ocaml" {>= "4.14"}
+  "cppo" {>= "1.7.0"}
+  "monolith" {with-test}
+  "ocamlfind" {with-test}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/fpottier/hachis.git"
+url {
+  src: "https://github.com/fpottier/hachis/archive/20240918.tar.gz"
+  checksum: [
+    "md5=1dd338011c4388eded0babef37c43de6"
+    "sha512=63008e86dd295b208c710260e52ccf8799ce8a48bd49e044c638c0b100141bfc3b6b0b16fe7d892280369def68f1a9e146a51d721074729bb61984fd4c7dbc7e"
+  ]
+}