diff --git a/flake.lock b/flake.lock
index 9ab6df6..f88daae 100644
--- a/flake.lock
+++ b/flake.lock
@@ -19,17 +19,36 @@
       }
     },
     "nixpkgs": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_2"
+      },
+      "locked": {
+        "lastModified": 1733437725,
+        "narHash": "sha256-ridu0NcO4Dr2TsHqPE+kh58xTHcXg7IHq/FF74KrP/g=",
+        "owner": "nix-ocaml",
+        "repo": "nix-overlays",
+        "rev": "03b85ffd6c37255829d475f3584f8d8a1556d5f2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-ocaml",
+        "repo": "nix-overlays",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
       "locked": {
         "lastModified": 1733380312,
         "narHash": "sha256-ywntxT10Om755wkB9tYgJwEwELQZKYAO5WcNuHv1vjI=",
-        "owner": "nixOS",
+        "owner": "NixOS",
         "repo": "nixpkgs",
         "rev": "a772498086eac57d97065a980a21fc0f304e3192",
         "type": "github"
       },
       "original": {
-        "owner": "nixOS",
+        "owner": "NixOS",
         "repo": "nixpkgs",
+        "rev": "a772498086eac57d97065a980a21fc0f304e3192",
         "type": "github"
       }
     },
diff --git a/flake.nix b/flake.nix
index 1e2f7dd..0b86b5c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,9 +1,14 @@
 {
   inputs = {
-    nixpkgs.url = "github:nixOS/nixpkgs";
+    nixpkgs.url = "github:nix-ocaml/nix-overlays";
     flake-utils.url = "github:numtide/flake-utils";
   };
 
+  nixConfig = {
+    extra-substituters = "https://anmonteiro.nix-cache.workers.dev";
+    extra-trusted-public-keys = "ocaml.nix-cache.com-1:/xI2h2+56rwFfKyyFVbkJSeGqSIYMC/Je+7XXqGKDIY=";
+  };
+
   outputs = {
     self,
     nixpkgs,
@@ -13,9 +18,10 @@
   in
     flake-utils.lib.eachDefaultSystem (
       system: let
-        pkgs = import nixpkgs {
-          inherit system;
-        };
+        pkgs = nixpkgs.legacyPackages.${system};
+        # import nixpkgs {
+        #   inherit system;
+        # };
         inherit (pkgs) mkShell ocamlPackages;
         inherit
           (ocamlPackages)
@@ -94,12 +100,12 @@
       }
     )
     // {
-      nixosModules.culr = import ./nix/module.nix {culrOverlay = self.overlays.culr;};
+      nixosModules.culr = import ./nix/module.nix {overlays = [self.overlays.culr self.inputs.nixpkgs.overlays.default];};
 
       overlays.culr = final: prev: let
         ocaml-deps = let
           inherit
-            (prev.ocamlPackages)
+            (final.ocamlPackages)
             dune_3
             ocaml
             angstrom
diff --git a/nix/module.nix b/nix/module.nix
index b79d426..b44cb16 100644
--- a/nix/module.nix
+++ b/nix/module.nix
@@ -1,4 +1,4 @@
-{culrOverlay}: {
+{overlays}: {
   imports = [./culr-module.nix];
-  nixpkgs.overlays = [culrOverlay];
+  nixpkgs.overlays = overlays;
 }