diff --git a/nix/camlp5.nix b/nix/camlp5.nix
deleted file mode 100644
index 32622ab43f783ea7b6e2e1fd007a297bc6985414..0000000000000000000000000000000000000000
--- a/nix/camlp5.nix
+++ /dev/null
@@ -1,59 +0,0 @@
-
-{ lib
-, stdenv
-, fetchFromGitHub
-, findlib
-, camlp-streams
-, ocaml
-, ocaml-compiler-libs
-, perl
-}:
-
-if lib.versionOlder ocaml.version "4.02"
-|| lib.versionOlder "4.15" ocaml.version
-then throw "camlp5 is not available for OCaml ${ocaml.version}"
-else
-
-stdenv.mkDerivation rec {
-
-  pname = "camlp5";
-  version = "8.00.03";
-
-  src = fetchFromGitHub {
-    owner = "camlp5";
-    repo = "camlp5";
-    rev = "rel${version}";
-    sha256 = "1fnvmaw9cland09pjx5h6w3f6fz9s23l4nbl4m9fcaa2i4dpraz6";
-  };
-
-  buildInputs = [ findlib camlp-streams ocaml perl ];
-
-  prefixKey = "-prefix ";
-
-  preConfigure = ''
-    configureFlagsArray=(--strict -libdir $out/lib/ocaml/${ocaml.version}/site-lib)
-    patchShebangs ./config/find_stuffversion.pl
-    patchShebangs ./etc/META.pl
-  '';
-
-  buildPhase = ''
-    make world.opt
-    make all
-  '';
-
-  dontStrip = true;
-
-  meta = with lib; {
-    description = "Preprocessor-pretty-printer for OCaml";
-    longDescription = ''
-      Camlp5 is a preprocessor and pretty-printer for OCaml programs.
-      It also provides parsing and printing tools.
-    '';
-    homepage = "https://camlp5.github.io/";
-    license = licenses.bsd3;
-    platforms = ocaml.meta.platforms or [];
-    maintainers = with maintainers; [
-      maggesi vbgl
-    ];
-  };
-}
diff --git a/nix/ocamlgraph.nix b/nix/ocamlgraph.nix
deleted file mode 100644
index 66b1c4d3ec7ee8fbeba9cb9578d429173857e5f7..0000000000000000000000000000000000000000
--- a/nix/ocamlgraph.nix
+++ /dev/null
@@ -1,26 +0,0 @@
-{ lib, fetchurl, buildDunePackage, stdlib-shims }:
-
-buildDunePackage rec {
-  pname = "ocamlgraph";
-  version = "2.1.0";
-
-  src = fetchurl {
-    url = "https://github.com/backtracking/ocamlgraph/releases/download/${version}/ocamlgraph-${version}.tbz";
-    sha256 = "sha256-D5YsNvklPfI5OVWvQbB0tqQmsvkqne95WyAFtX0wLWU=";
-  };
-
-  minimalOCamlVersion = "4.08";
-  useDune2 = true;
-
-  propagatedBuildInputs = [
-    stdlib-shims
-  ];
-
-  meta = with lib; {
-      homepage = "http://ocamlgraph.lri.fr/";
-      downloadPage = "https://github.com/backtracking/ocamlgraph";
-      description = "Graph library for OCaml";
-      license = licenses.gpl2Oss;
-      maintainers = with maintainers; [ ];
-  };
-}
diff --git a/nix/ocplib-simplex.nix b/nix/ocplib-simplex.nix
new file mode 100644
index 0000000000000000000000000000000000000000..474f69546d1a10929c579a3bf0366fed1f392414
--- /dev/null
+++ b/nix/ocplib-simplex.nix
@@ -0,0 +1,33 @@
+{ stdenv, lib, fetchFromGitHub, autoreconfHook, ocaml, findlib }:
+
+let
+  pname = "ocplib-simplex";
+  version = "0.4";
+in
+
+stdenv.mkDerivation {
+  name = "ocaml${ocaml.version}-${pname}-${version}";
+
+  src = fetchFromGitHub {
+    owner = "OCamlPro-Iguernlala";
+    repo = pname;
+    rev = "v${version}";
+    sha256 = "09niyidrjzrj8g1qwx4wgsdf5m6cwrnzg7zsgala36jliic4di60";
+  };
+
+  nativeBuildInputs = [ autoreconfHook ocaml findlib ];
+
+  strictDeps = true;
+
+  installFlags = [ "LIBDIR=$(OCAMLFIND_DESTDIR)" ];
+
+  createFindlibDestdir = true;
+
+  meta = {
+    description = "An OCaml library implementing a simplex algorithm, in a functional style, for solving systems of linear inequalities";
+    homepage = "https://github.com/OCamlPro-Iguernlala/ocplib-simplex";
+    inherit (ocaml.meta) platforms;
+    license = lib.licenses.lgpl21;
+    maintainers = [ lib.maintainers.vbgl ];
+  };
+}
diff --git a/nix/pkgs.nix b/nix/pkgs.nix
index 25c355331580ddc8845fd3b16f76044ebbc0cd2e..6945e8043c4329525e805cc58b2cc70a797023f4 100644
--- a/nix/pkgs.nix
+++ b/nix/pkgs.nix
@@ -3,13 +3,11 @@ let
   ocamlOverlay = oself: osuper: {
     # External Packages
     alt-ergo = oself.callPackage ./alt-ergo.nix {};
-    camlp5 = oself.callPackage ./camlp5.nix {};
     combinetura = oself.callPackage ./combinetura.nix {};
     headache = oself.callPackage ./headache.nix {};
     mlmpfr = oself.callPackage ./mlmpfr.nix {};
-    ocamlgraph = oself.callPackage ./ocamlgraph.nix {};
+    ocplib-simplex = oself.callPackage ./ocplib-simplex.nix {};
     why3 = oself.callPackage ./why3.nix {};
-    ppx_deriving_yaml = oself.callPackage ./ppx_deriving_yaml.nix {};
 
     # Helpers
     mk_tests = oself.callPackage ./mk_tests.nix {};
diff --git a/nix/ppx_deriving_yaml.nix b/nix/ppx_deriving_yaml.nix
deleted file mode 100644
index 4b1e177f30bea44777844c0b7cd2bce8ede92056..0000000000000000000000000000000000000000
--- a/nix/ppx_deriving_yaml.nix
+++ /dev/null
@@ -1,23 +0,0 @@
-{ lib, buildDunePackage, fetchurl, ppxlib, alcotest, ppx_deriving, yaml }:
-
-buildDunePackage rec {
-  pname = "ppx_deriving_yaml";
-  version = "0.2.1";
-
-  minimalOCamlVersion = "4.08";
-  duneVersion = "3";
-
-  src = fetchurl {
-    url = "https://github.com/patricoferris/ppx_deriving_yaml/releases/download/v${version}/ppx_deriving_yaml-${version}.tbz";
-    sha256 = "sha256-3vmay8UY7d3j96VOQ+D3oYEotzVls91F51ebXWQ/9SQ=";
-  };
-
-  propagatedBuildInputs = [ ppxlib ppx_deriving yaml ];
-
-  meta = {
-    description = "A YAML codec generator for OCaml";
-    homepage = "https://github.com/patricoferris/ppx_deriving_yaml";
-    license = lib.licenses.isc;
-    maintainers = [ ];
-  };
-}
diff --git a/nix/sources.json b/nix/sources.json
index f88cc85ea5836aba1279476bd7f3846865c1f747..cb4337bbbcbea7ea7b46ef3304ea1af627b0eb28 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -29,10 +29,10 @@
         "homepage": "https://github.com/NixOS/nixpkgs",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f292b4964cb71f9dfbbd30dc9f511d6165cd109b",
-        "sha256": "01yzrkrb60dd2y2y3fh4939z374hf5pa92q8axfcygqlnbk3jpb4",
+        "rev": "fdd898f8f79e8d2f99ed2ab6b3751811ef683242",
+        "sha256": "05i97acjry4pk1br8glwl97gbfjafq058kblpfpd39r0qr8j6x4s",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/f292b4964cb71f9dfbbd30dc9f511d6165cd109b.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/fdd898f8f79e8d2f99ed2ab6b3751811ef683242.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "why3": {