diff --git a/pkgs/development/compilers/heptagon/default.nix b/pkgs/by-name/he/heptagon/package.nix
similarity index 83%
rename from pkgs/development/compilers/heptagon/default.nix
rename to pkgs/by-name/he/heptagon/package.nix
index 0bfdb702aaaf..be1b69a3a263 100644
--- a/pkgs/development/compilers/heptagon/default.nix
+++ b/pkgs/by-name/he/heptagon/package.nix
@@ -4,6 +4,7 @@
   fetchFromGitLab,
   makeWrapper,
   ocamlPackages,
+  fetchpatch,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -18,6 +19,13 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-b4O48MQT3Neh8a1Z5wRgS701w6XrwpsbSMprlqTT+CE=";
   };
 
+  patches = [
+    (fetchpatch {
+      url = "https://gitlab.inria.fr/synchrone/heptagon/-/commit/f10405e385ca25dc737727e0c210a44986929bf0.patch";
+      hash = "sha256-Sn55jEoRDYnEUg4SjuBDCNN4TNl2Dwn1fTjb9O8O1bo=";
+    })
+  ];
+
   strictDeps = true;
 
   nativeBuildInputs = with ocamlPackages; [
diff --git a/pkgs/development/ocaml-modules/config-file/default.nix b/pkgs/development/ocaml-modules/config-file/default.nix
index f20a7d9b113f..4bb913d544bf 100644
--- a/pkgs/development/ocaml-modules/config-file/default.nix
+++ b/pkgs/development/ocaml-modules/config-file/default.nix
@@ -7,30 +7,34 @@
   camlp4,
 }:
 
-stdenv.mkDerivation rec {
-  pname = "ocaml-config-file";
-  version = "1.2";
+lib.throwIf (lib.versionAtLeast ocaml.version "5.0")
+  "config-file is not available for OCaml ${ocaml.version}"
 
-  src = fetchurl {
-    url = "https://forge.ocamlcore.org/frs/download.php/1387/config-file-${version}.tar.gz";
-    sha256 = "1b02yxcnsjhr05ssh2br2ka4hxsjpdw34ldl3nk33wfnkwk7g67q";
-  };
+  stdenv.mkDerivation
+  rec {
+    pname = "ocaml-config-file";
+    version = "1.2";
 
-  nativeBuildInputs = [
-    ocaml
-    findlib
-    camlp4
-  ];
+    src = fetchurl {
+      url = "https://forge.ocamlcore.org/frs/download.php/1387/config-file-${version}.tar.gz";
+      sha256 = "1b02yxcnsjhr05ssh2br2ka4hxsjpdw34ldl3nk33wfnkwk7g67q";
+    };
 
-  strictDeps = true;
+    nativeBuildInputs = [
+      ocaml
+      findlib
+      camlp4
+    ];
 
-  createFindlibDestdir = true;
+    strictDeps = true;
 
-  meta = {
-    homepage = "http://config-file.forge.ocamlcore.org/";
-    platforms = ocaml.meta.platforms or [ ];
-    description = "OCaml library used to manage the configuration file(s) of an application";
-    license = lib.licenses.lgpl2Plus;
-    maintainers = with lib.maintainers; [ vbgl ];
-  };
-}
+    createFindlibDestdir = true;
+
+    meta = {
+      homepage = "http://config-file.forge.ocamlcore.org/";
+      platforms = ocaml.meta.platforms or [ ];
+      description = "OCaml library used to manage the configuration file(s) of an application";
+      license = lib.licenses.lgpl2Plus;
+      maintainers = with lib.maintainers; [ vbgl ];
+    };
+  }
diff --git a/pkgs/development/ocaml-modules/ulex/default.nix b/pkgs/development/ocaml-modules/ulex/default.nix
index bbc26d8650f8..ac98285c101f 100644
--- a/pkgs/development/ocaml-modules/ulex/default.nix
+++ b/pkgs/development/ocaml-modules/ulex/default.nix
@@ -23,39 +23,43 @@ let
       };
 in
 
-stdenv.mkDerivation rec {
-  name = "ocaml${ocaml.version}-${pname}-${version}";
-  inherit (param) version;
+lib.throwIf (lib.versionAtLeast ocaml.version "5.0")
+  "ulex is not available for OCaml ${ocaml.version}"
 
-  src = fetchFromGitHub {
-    owner = "whitequark";
-    repo = pname;
-    rev = "v${version}";
-    inherit (param) sha256;
-  };
+  stdenv.mkDerivation
+  rec {
+    name = "ocaml${ocaml.version}-${pname}-${version}";
+    inherit (param) version;
 
-  createFindlibDestdir = true;
+    src = fetchFromGitHub {
+      owner = "whitequark";
+      repo = pname;
+      rev = "v${version}";
+      inherit (param) sha256;
+    };
 
-  nativeBuildInputs = [
-    ocaml
-    findlib
-    ocamlbuild
-    camlp4
-  ];
-  propagatedBuildInputs = [ camlp4 ];
+    createFindlibDestdir = true;
 
-  strictDeps = true;
+    nativeBuildInputs = [
+      ocaml
+      findlib
+      ocamlbuild
+      camlp4
+    ];
+    propagatedBuildInputs = [ camlp4 ];
 
-  buildFlags = [
-    "all"
-    "all.opt"
-  ];
+    strictDeps = true;
 
-  meta = {
-    inherit (src.meta) homepage;
-    description = "Lexer generator for Unicode and OCaml";
-    license = lib.licenses.mit;
-    inherit (ocaml.meta) platforms;
-    maintainers = [ lib.maintainers.roconnor ];
-  };
-}
+    buildFlags = [
+      "all"
+      "all.opt"
+    ];
+
+    meta = {
+      inherit (src.meta) homepage;
+      description = "Lexer generator for Unicode and OCaml";
+      license = lib.licenses.mit;
+      inherit (ocaml.meta) platforms;
+      maintainers = [ lib.maintainers.roconnor ];
+    };
+  }
diff --git a/pkgs/development/tools/ocaml/camlp4/default.nix b/pkgs/development/tools/ocaml/camlp4/default.nix
index ac76bfba3f32..89cdc1eb6ec3 100644
--- a/pkgs/development/tools/ocaml/camlp4/default.nix
+++ b/pkgs/development/tools/ocaml/camlp4/default.nix
@@ -4,10 +4,12 @@
   fetchzip,
   which,
   ocaml,
+  camlp-streams,
   ocamlbuild,
+  findlib,
 }:
 
-if lib.versionAtLeast ocaml.version "4.15" then
+if lib.versionAtLeast ocaml.version "5.4" then
   throw "camlp4 is not available for OCaml ${ocaml.version}"
 else
 
@@ -66,6 +68,22 @@ else
           version = "4.14+1";
           sha256 = "sha256-cPN3GioZT/Zt6uzbjGUPEGVJcPQdsAnCkU/AQoPfvuo=";
         };
+        "5.0" = {
+          version = "5.0";
+          sha256 = "sha256-oZptFNPUEAq5YlcqAoDWfLghGMF9AN7E7hUN55SAX+4=";
+        };
+        "5.1" = {
+          version = "5.1";
+          sha256 = "sha256-Ubedjg3BeHA0bJbEalQN9eEk5+LRAI/er+8mWfVYchg=";
+        };
+        "5.2" = {
+          version = "5.2";
+          sha256 = "sha256-lzbc9xsgeYlbVf71O+PWYS14QivAH1aPdnvWhe0HHME=";
+        };
+        "5.3" = {
+          version = "5.3";
+          sha256 = "sha256-V/kKhTP9U4jWDFuQKuB7BS3XICg1lq/2Avj7UJR55+k=";
+        };
       }
       .${ocaml.meta.branch};
   in
@@ -81,9 +99,18 @@ else
 
     strictDeps = true;
 
-    nativeBuildInputs = [
-      which
-      ocaml
+    nativeBuildInputs =
+      [
+        which
+        ocaml
+        ocamlbuild
+      ]
+      ++ lib.optionals (lib.versionAtLeast ocaml.version "5.0") [
+        findlib
+      ];
+
+    buildInputs = lib.optionals (lib.versionAtLeast ocaml.version "5.0") [
+      camlp-streams
       ocamlbuild
     ];
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index c86ab73d455d..770d6c409fab 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -6331,10 +6331,6 @@ with pkgs;
     inherit (emacs.pkgs.melpaStablePackages) irony;
   };
 
-  heptagon = callPackage ../development/compilers/heptagon {
-    ocamlPackages = ocaml-ng.ocamlPackages_4_14;
-  };
-
   openjfx17 = openjfx;
   openjfx21 = callPackage ../by-name/op/openjfx/package.nix { featureVersion = "21"; };
   openjfx23 = callPackage ../by-name/op/openjfx/package.nix { featureVersion = "23"; };