diff --git a/.gitignore b/.gitignore
index 3af7b8b..3563d8a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+result
 _build
 test.sh
 fatal.sh
diff --git a/dune-project b/dune-project
index c34018c..4488d76 100644
--- a/dune-project
+++ b/dune-project
@@ -21,12 +21,14 @@
  (synopsis "A shell library")
  (description "A library for writing shells")
  (depends
-   morbig
    linenoise
+   visitors
    re
    terminal
+  (menhir
+   (= 20250912))
   (yojson
-   (>= 2.2.2))
+   (= 2.2.2))
   (ppxlib
    (>= 0.37.0))
   (ppx_deriving_yojson
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..16c0f82
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,193 @@
+{
+  "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1747046372,
+        "narHash": "sha256-CIVLLkVgvHYbgI2UpXvIIBJ12HWgX+fjA8Xf8PUmqCY=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "mirage-opam-overlays": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1710922379,
+        "narHash": "sha256-j4QREQDUf8oHOX7qg6wAOupgsNQoYlufxoPrgagD+pY=",
+        "owner": "dune-universe",
+        "repo": "mirage-opam-overlays",
+        "rev": "797cb363df3ff763c43c8fbec5cd44de2878757e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "dune-universe",
+        "repo": "mirage-opam-overlays",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1770473678,
+        "narHash": "sha256-2jWALGZyRKEW4ycxfAqG04UuZCqJwt34sfJnJkf4jzo=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "c03cfff2b79dd525b374df7022ab3499ac12e59d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "opam-nix": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "mirage-opam-overlays": "mirage-opam-overlays",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "opam-overlays": "opam-overlays",
+        "opam-repository": [
+          "opam-repository"
+        ],
+        "opam2json": "opam2json"
+      },
+      "locked": {
+        "lastModified": 1769900026,
+        "narHash": "sha256-O1cK8GVRNDKvAXU0mZjqpmftRnAeyDgyP7lf/3P/Pdg=",
+        "owner": "tweag",
+        "repo": "opam-nix",
+        "rev": "1f373ef8c4cc1237a74c681b47bbdbdf7ab185a6",
+        "type": "github"
+      },
+      "original": {
+        "owner": "tweag",
+        "repo": "opam-nix",
+        "type": "github"
+      }
+    },
+    "opam-overlays": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1741116009,
+        "narHash": "sha256-Z0PIW82fHJFvAv/JYpAffnp2DaOjLhsPutqyIrORZd0=",
+        "owner": "dune-universe",
+        "repo": "opam-overlays",
+        "rev": "e031bb64e33bf93be963e9a38b28962e6e14381f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "dune-universe",
+        "repo": "opam-overlays",
+        "type": "github"
+      }
+    },
+    "opam-repository": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1770398609,
+        "narHash": "sha256-umhfG0YRCc59Gw7Xm8Um6gPSC6vaJo7knIt9EfULs1Q=",
+        "owner": "ocaml",
+        "repo": "opam-repository",
+        "rev": "340ee6fd1ff10d0fce25e21ba1caca9ed1cfec68",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ocaml",
+        "repo": "opam-repository",
+        "type": "github"
+      }
+    },
+    "opam2json": {
+      "inputs": {
+        "nixpkgs": [
+          "opam-nix",
+          "nixpkgs"
+        ],
+        "systems": "systems_2"
+      },
+      "locked": {
+        "lastModified": 1749457947,
+        "narHash": "sha256-+QVm+HOYikF3wUhqSIV8qJbE/feSG+p48fgxIosbHS0=",
+        "owner": "tweag",
+        "repo": "opam2json",
+        "rev": "0ecd66fc2bfb25d910522c990dd36412259eac1f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "tweag",
+        "repo": "opam2json",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs",
+        "opam-nix": "opam-nix",
+        "opam-repository": "opam-repository"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
+    "systems_2": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..b041a0b
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,54 @@
+# Mostly copied from RyanGibb/eon
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs";
+    opam-nix.url = "github:tweag/opam-nix";
+    flake-utils.url = "github:numtide/flake-utils";
+    opam-nix.inputs.nixpkgs.follows = "nixpkgs";
+    opam-nix.inputs.flake-utils.follows = "flake-utils";
+    # maintain a different opam-repository to those pinned upstream
+    opam-repository = {
+      url = "github:ocaml/opam-repository";
+      flake = false;
+    };
+    self.submodules = true;
+    opam-nix.inputs.opam-repository.follows = "opam-repository";
+  };
+  outputs = { self, nixpkgs, flake-utils, opam-nix, ... }@inputs:
+    # create outputs for each default system
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        package = "merry";
+        pkgs = nixpkgs.legacyPackages.${system};
+        opam-nix-lib = opam-nix.lib.${system};
+        devPackagesQuery = {
+          ocaml-lsp-server = "*";
+          ocamlformat = "*";
+          utop = "*";
+        };
+        query = {
+          ocaml-base-compiler = "*";
+        };
+        scope =
+          # recursive finds vendored dependancies in duniverse
+          opam-nix-lib.buildOpamProject' { recursive = true; } ./. (query // devPackagesQuery);
+      in {
+        packages.default = scope.${package};
+        defaultPackage = scope.${package};
+
+        devShells.default = let
+          devPackages = builtins.attrValues
+            (pkgs.lib.getAttrs (builtins.attrNames devPackagesQuery) scope);
+        in pkgs.mkShell {
+          inputsFrom = [ scope.${package} ];
+          buildInputs = devPackages;
+        };
+      }) // {
+        nixosModules = {
+          default.imports = [ (import ./module.nix self.packages) ];
+        };
+
+        formatter = nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed
+          (system: nixpkgs.legacyPackages.${system}.nixfmt);
+      };
+}
diff --git a/merry.opam b/merry.opam
index d258ac2..3f09afb 100644
--- a/merry.opam
+++ b/merry.opam
@@ -9,11 +9,12 @@ tags: ["add topics" "to describe" "your" "project"]
 doc: "https://url/to/documentation"
 depends: [
   "dune" {>= "3.20"}
-  "morbig"
   "linenoise"
+  "visitors"
   "re"
   "terminal"
-  "yojson" {>= "2.2.2"}
+  "menhir" {= "20250912"}
+  "yojson" {= "2.2.2"}
   "ppxlib" {>= "0.37.0"}
   "ppx_deriving_yojson" {>= "3.10.0"}
   "globlon" {>= "0"}