diff --git a/packages/prelude/prelude.0.4/opam b/packages/prelude/prelude.0.4/opam
new file mode 100644
index 00000000000..0e21931ebc2
--- /dev/null
+++ b/packages/prelude/prelude.0.4/opam
@@ -0,0 +1,43 @@
+opam-version: "2.0"
+synopsis: "OCaml library hiding stuff from the stdlib"
+description:
+  "Prelude is an OCaml library hiding a lot of stuff from the stdlib to enforce good programming practices."
+maintainer: ["Léo Andrès <contact@ndrs.fr>"]
+authors: ["Léo Andrès <contact@ndrs.fr>"]
+license: "AGPL-3.0-or-later"
+tags: ["prelude" "stdlib" "safe" "exception" "layer" "hide"]
+homepage: "https://git.zapashcanon.fr/zapashcanon/prelude"
+bug-reports: "https://git.zapashcanon.fr/zapashcanon/prelude/issues"
+depends: [
+  "dune" {>= "3.0"}
+  "ocaml" {>= "4.13"}
+  "bos"
+  "cmdliner"
+  "fmt"
+  "fpath"
+  "ocamlformat" {with-dev-setup}
+  "odoc" {with-dev-setup}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://git.zapashcanon.fr/zapashcanon/prelude.git"
+url {
+  src: "https://git.zapashcanon.fr/zapashcanon/prelude/archive/0.4.tar.gz"
+  checksum: [
+    "sha256=858fd4291ea8767c6d238d7c5976107589053157dd4a6d53fa49a0451d7db7ab"
+    "sha512=beeacb29c18794854bfdf4d9ca53b24a35e64dbcc07e44fb56087cb14bbb4f8ad21c26eea202b04dd075c4fd84068ae997bd081a51989a6906c47fd58355da5f"
+  ]
+}
diff --git a/packages/smtml/smtml.0.2.4/opam b/packages/smtml/smtml.0.2.4/opam
index abfc88cd496..28a978ecdbc 100644
--- a/packages/smtml/smtml.0.2.4/opam
+++ b/packages/smtml/smtml.0.2.4/opam
@@ -11,7 +11,7 @@ bug-reports: "https://github.com/formalsec/smtml/issues"
 depends: [
   "dune" {>= "3.10"}
   "ocaml" {>= "4.14.0"}
-  "prelude" {>= "0.3"}
+  "prelude" {= "0.3"}
   "ocaml_intrinsics"
   "fmt" {>= "0.8.7"}
   "cmdliner" {>= "1.2.0"}
diff --git a/packages/smtml/smtml.0.2.5/opam b/packages/smtml/smtml.0.2.5/opam
index 88ee8b8d3b7..305454673c6 100644
--- a/packages/smtml/smtml.0.2.5/opam
+++ b/packages/smtml/smtml.0.2.5/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/formalsec/smtml/issues"
 depends: [
   "dune" {>= "3.10"}
   "ocaml" {>= "4.14.0"}
-  "prelude" {>= "0.3"}
+  "prelude" {= "0.3"}
   "ocaml_intrinsics"
   "fmt" {>= "0.8.7"}
   "cmdliner" {>= "1.2.0"}
diff --git a/packages/smtml/smtml.0.3.1/opam b/packages/smtml/smtml.0.3.1/opam
index d51add9c8e0..1cc79855ab9 100644
--- a/packages/smtml/smtml.0.3.1/opam
+++ b/packages/smtml/smtml.0.3.1/opam
@@ -28,7 +28,7 @@ depends: [
   "ocaml" {>= "4.14.0"}
   "ocaml_intrinsics"
   "patricia-tree" {>= "0.10.0"}
-  "prelude" {>= "0.3"}
+  "prelude" {= "0.3"}
   "rusage"
   "yojson" {>= "1.6.0"}
   "zarith" {>= "1.5"}
diff --git a/packages/smtml/smtml.0.4.0/opam b/packages/smtml/smtml.0.4.0/opam
index 86635282544..26fe5623c6c 100644
--- a/packages/smtml/smtml.0.4.0/opam
+++ b/packages/smtml/smtml.0.4.0/opam
@@ -28,7 +28,7 @@ depends: [
   "ocaml" {>= "4.14.0"}
   "ocaml_intrinsics"
   "patricia-tree" {>= "0.10.0"}
-  "prelude" {>= "0.3"}
+  "prelude" {= "0.3"}
   "rusage"
   "scfg"
   "yojson" {>= "1.6.0"}
diff --git a/packages/smtml/smtml.0.4.1/opam b/packages/smtml/smtml.0.4.1/opam
index e9aebe5332e..6c75770cf48 100644
--- a/packages/smtml/smtml.0.4.1/opam
+++ b/packages/smtml/smtml.0.4.1/opam
@@ -28,7 +28,7 @@ depends: [
   "ocaml" {>= "4.14.0"}
   "ocaml_intrinsics"
   "patricia-tree" {>= "0.10.0"}
-  "prelude" {>= "0.3"}
+  "prelude" {= "0.3"}
   "rusage"
   "scfg"
   "yojson" {>= "1.6.0"}