diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..817e409
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,11 @@
+on: [push, pull_request]
+name: build
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: lint
+        uses: Roang-zero1/factorio-mod-luacheck@master
+        with:
+          luacheckrc_url: ""
diff --git a/.luacheckrc b/.luacheckrc
new file mode 100644
index 0000000..14397b2
--- /dev/null
+++ b/.luacheckrc
@@ -0,0 +1,15 @@
+unused_args = false
+allow_defined_top = true
+max_line_length = 999
+
+read_globals = {
+    string = {fields = {"split", "trim"}},
+    table = {fields = {"copy", "getn", "indexof"}},
+
+    "minetest", "DIR_DELIM",
+    "vector", "VoxelArea",
+}
+
+ignore = {
+    "vertList",
+}
diff --git a/README.md b/README.md
index e6d0902..73a9a27 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,8 @@
 # Meshport (Minetest Mesh Exporter)
 
+[![Build status](https://github.com/random-geek/meshport/workflows/build/badge.svg)](https://github.com/random-geek/meshport/actions)
+[![License](https://img.shields.io/badge/license-LGPLv3.0%2B-blue.svg)](https://www.gnu.org/licenses/lgpl-3.0.en.html)
+
 ![screenshot](screenshot.png)
 
 Meshport is a mod which allows easy exporting of scenes from Minetest to `.obj` files, complete with materials and textures. These models can be imported directly into Blender or another 3D program for rendering and animation.
diff --git a/nodebox.lua b/nodebox.lua
index af9d537..b566a00 100644
--- a/nodebox.lua
+++ b/nodebox.lua
@@ -98,7 +98,7 @@ function meshport.Boxes:to_faces(nodeTiles, pos, facedir)
 			{{x = b[4], y = b[2]}, {x = b[4], y = b[5]}, {x = b[1], y = b[5]}, {x = b[1], y = b[2]}}, -- Z-
 		}
 
-		local tileIdx, vertNorm
+		local vertNorm
 
 		for i = 1, 6 do
 			-- Fix offset texture coordinates.