diff --git a/flake.lock b/flake.lock
index aa94486..75848b9 100644
--- a/flake.lock
+++ b/flake.lock
@@ -20,30 +20,46 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1733380312,
-        "narHash": "sha256-ywntxT10Om755wkB9tYgJwEwELQZKYAO5WcNuHv1vjI=",
+        "lastModified": 1733749988,
+        "narHash": "sha256-+5qdtgXceqhK5ZR1YbP1fAUsweBIrhL38726oIEAtDs=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "bc27f0fde01ce4e1bfec1ab122d72b7380278e68",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1733838633,
+        "narHash": "sha256-51x/FRiqMGQMyP+aSTp5b36WxsvT7q9KYtW2f+7+HoI=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a772498086eac57d97065a980a21fc0f304e3192",
+        "rev": "cdb5bd9f4fe066d1726cd848ad5858eb36a2ca93",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a772498086eac57d97065a980a21fc0f304e3192",
+        "rev": "cdb5bd9f4fe066d1726cd848ad5858eb36a2ca93",
         "type": "github"
       }
     },
-    "nixpkgs-oc": {
+    "ocaml-overlay": {
       "inputs": {
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1733437725,
-        "narHash": "sha256-ridu0NcO4Dr2TsHqPE+kh58xTHcXg7IHq/FF74KrP/g=",
+        "lastModified": 1733872709,
+        "narHash": "sha256-CSjVHftyEGmkDeheoWDjQECIrgASNy8FNc0fqIFvcwM=",
         "owner": "nix-ocaml",
         "repo": "nix-overlays",
-        "rev": "03b85ffd6c37255829d475f3584f8d8a1556d5f2",
+        "rev": "8a82971570aafb4233340ef429ba672fd780b5ac",
         "type": "github"
       },
       "original": {
@@ -55,7 +71,8 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs-oc": "nixpkgs-oc"
+        "nixpkgs": "nixpkgs",
+        "ocaml-overlay": "ocaml-overlay"
       }
     },
     "systems": {
diff --git a/flake.nix b/flake.nix
index 8cfdba2..a98b9a5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,6 +1,7 @@
 {
   inputs = {
-    nixpkgs-oc.url = "github:nix-ocaml/nix-overlays";
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    ocaml-overlay.url = "github:nix-ocaml/nix-overlays";
     flake-utils.url = "github:numtide/flake-utils";
   };
 
@@ -11,17 +12,18 @@
 
   outputs = {
     self,
-    nixpkgs-oc,
+    nixpkgs,
+    ocaml-overlay,
     flake-utils,
   }: let
     version = builtins.toString self.lastModified;
   in
     flake-utils.lib.eachDefaultSystem (
       system: let
-        pkgs = nixpkgs-oc.legacyPackages.${system};
-        # import nixpkgs {
-        #   inherit system;
-        # };
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ocaml-overlay.overlays.default];
+        };
         inherit (pkgs) mkShell ocamlPackages;
         inherit
           (ocamlPackages)
@@ -104,7 +106,7 @@
       }
     )
     // {
-      nixosModules.culr = import ./nix/module.nix {overlays = [nixpkgs-oc.overlays.default self.overlays.culr];};
+      nixosModules.culr = import ./nix/module.nix {overlays = [ocaml-overlay.overlays.default self.overlays.culr];};
 
       overlays.culr = final: prev: let
         ocaml-deps = let