diff --git a/.circleci/config.yml b/.circleci/config.yml
index 253d2ab9c..2cf67ad37 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -12,7 +12,8 @@ common_steps: &common_steps
     - run:
         name: "Install npm"
         command: |
-          sudo apt-get install -y nodejs npm
+          sudo apt update
+          sudo apt install -y nodejs npm
           mkdir -p ~/.npm-global
           npm config set prefix $NPM_CONFIG_PREFIX
     - checkout
@@ -24,12 +25,12 @@ common_steps: &common_steps
     - run:
         name: "Initialize opam"
         command: |
-          sudo apt-get install -y m4
+          sudo apt install -y m4
           opam remote set-url default https://opam.ocaml.org
     - run:
         name: "Install deps"
         command: |
-          sudo apt-get install -y pkg-config libncurses5-dev
+          sudo apt install -y pkg-config libncurses5-dev
           opam update
           opam install -y dune menhir utop
     - run:
@@ -148,13 +149,14 @@ jobs:
           name: "Install npm"
           command: |
             curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
-            sudo apt-get install -y nodejs
+            sudo apt update
+            sudo apt install -y nodejs
             mkdir -p ~/.npm-global
             npm config set prefix $NPM_CONFIG_PREFIX
       - run:
           name: "Install m4"
           command: |
-            sudo apt-get install -y m4
+            sudo apt install -y m4
       - restore_cache:
           <<: *esy_cache_key
       - restore_cache:
diff --git a/flake.lock b/flake.lock
index 123e7cfaa..129e3f017 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,26 +2,11 @@
   "nodes": {
     "flake-utils": {
       "locked": {
-        "lastModified": 1659877975,
-        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
+        "lastModified": 1676283394,
+        "narHash": "sha256-XX2f9c3iySLCw54rJ/CZs+ZK6IQy7GXNY4nSOyu2QG4=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
-    "flake-utils_2": {
-      "locked": {
-        "lastModified": 1659877975,
-        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
+        "rev": "3db36a8b464d0c4532ba1c7dda728f4576d6d073",
         "type": "github"
       },
       "original": {
@@ -32,11 +17,11 @@
     },
     "nix-filter": {
       "locked": {
-        "lastModified": 1661201956,
-        "narHash": "sha256-RizGJH/buaw9A2+fiBf9WnXYw4LZABB5kMAZIEE5/T8=",
+        "lastModified": 1676294984,
+        "narHash": "sha256-hdLUa/3RH1VJ+gMUysQE0JGM4F2Q/tIIFbtoxAOurJQ=",
         "owner": "numtide",
         "repo": "nix-filter",
-        "rev": "3b821578685d661a10b563cba30b1861eec05748",
+        "rev": "fc282c5478e4141842f9644c239a41cfe9586732",
         "type": "github"
       },
       "original": {
@@ -47,36 +32,38 @@
     },
     "nixpkgs": {
       "inputs": {
-        "flake-utils": "flake-utils_2",
+        "flake-utils": [
+          "flake-utils"
+        ],
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1665818387,
-        "narHash": "sha256-5+Y365wu1RihKrth4KRnDepfIjlmD3f5fOby5NF9lfI=",
-        "owner": "anmonteiro",
+        "lastModified": 1677883479,
+        "narHash": "sha256-ehAvAzzRzyvSfoPv2jQI5pSaasUVJa5V8oe885YcyYA=",
+        "owner": "nix-ocaml",
         "repo": "nix-overlays",
-        "rev": "02c592db888ad96c37b0262956c01e1f6c0d7a0a",
+        "rev": "f332166f76369fec30ae6ae905b7226dbf1555fe",
         "type": "github"
       },
       "original": {
-        "owner": "anmonteiro",
+        "owner": "nix-ocaml",
         "repo": "nix-overlays",
         "type": "github"
       }
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1665739725,
-        "narHash": "sha256-+4gT1fslLg/EN1nnCzIxVSpPpgCME55zUYVkwmXiAS4=",
+        "lastModified": 1677845674,
+        "narHash": "sha256-9wy/QFibdJUp7WQUe50U5bZKocg3OOHBpJhpl5ddfbE=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a114755d05c1a590ece2e3ecff31e43e07334b5e",
+        "rev": "dcc47fef8bd1e91baeab8fb34a35337ab8f3a3fd",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a114755d05c1a590ece2e3ecff31e43e07334b5e",
+        "rev": "dcc47fef8bd1e91baeab8fb34a35337ab8f3a3fd",
         "type": "github"
       }
     },
diff --git a/flake.nix b/flake.nix
index 095e29a66..4e0a93f6f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,13 +3,14 @@
 
   inputs.nix-filter.url = "github:numtide/nix-filter";
   inputs.flake-utils.url = "github:numtide/flake-utils";
-  inputs.nixpkgs.url = "github:anmonteiro/nix-overlays";
+  inputs.nixpkgs.url = "github:nix-ocaml/nix-overlays";
+  inputs.nixpkgs.inputs.flake-utils.follows = "flake-utils";
 
   outputs = { self, nixpkgs, flake-utils, nix-filter }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = nixpkgs.legacyPackages."${system}".extend (self: super: {
-          ocamlPackages = super.ocaml-ng.ocamlPackages_5_00;
+          ocamlPackages = super.ocaml-ng.ocamlPackages_5_0;
         });
       in
       rec {