diff --git a/Models.cpp b/Models.cpp
index 85f0f3a..0af90f6 100644
--- a/Models.cpp
+++ b/Models.cpp
@@ -49,8 +49,8 @@ bool ckFaceHasAnyOtherRels(const std::vector<struct result> &results,
     auto oth = (r.x == f) ? r.y : r.x;
     all_filecodes.insert(oth.i);
     if (r.res == Relation::Equals
-    || r.res == Relation::Included && r.x == f
-    || r.res == Relation::Includes && r.y == f) {
+    || (r.res == Relation::Included && r.x == f)
+    || (r.res == Relation::Includes && r.y == f)) {
       where_exists.insert(oth.i);
       continue;
     }
@@ -102,6 +102,8 @@ std::string statements(struct result r, std::vector<struct Model> faces) {
     return st("A", B, A);
   case Relation::Intersects:
     return st("I", A, B);
+  case Relation::Irrelates:
+    return "";
   }
   return "";
 }
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..76e7ff9
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1787814960,
+        "narHash": "sha256-PYZq1qzCJXC2zGI0mH07vrZBsw6DRBAOX0jN1pPtqOQ=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "c27cdad491a991b11ed731760aa2ef8db0cb0410",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..222b19d
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,33 @@
+{
+  description = "Surface relation extractor for OCCT";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixpkgs-unstable";
+  };
+
+  outputs =
+    { self, nixpkgs }:
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+    in
+    {
+      devShells.${system}.default = pkgs.mkShell {
+        buildInputs = with pkgs; [
+          cmake
+          opencascade-occt
+          clang
+        ];
+      };
+      defaultPackage.x86_64-linux = pkgs.stdenv.mkDerivation {
+        pname = "OcctSurfacer";
+        version = "1.0.0";
+        src = ./.;
+        nativeBuildInputs = [
+          pkgs.cmake
+          pkgs.opencascade-occt
+        ];
+
+        cmakeFlags = [ "-DBUILD_TESTING=OFF" ];
+      };
+    };
+}