diff --git a/scripts/dev-local.test.mjs b/scripts/dev-local.test.mjs
new file mode 100644
index 0000000..19fea79
--- /dev/null
+++ b/scripts/dev-local.test.mjs
@@ -0,0 +1,13 @@
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+import test from 'node:test';
+import { fileURLToPath } from 'node:url';
+
+const launcherPath = fileURLToPath(new URL('./dev-local.sh', import.meta.url));
+
+test('native launcher retains a UTF-8 locale after sanitizing its environment', async () => {
+  const launcher = await readFile(launcherPath, 'utf8');
+  const nativeCommand = launcher.slice(launcher.indexOf('cmd_native() {'), launcher.indexOf('\ncase "${1:-up}" in'));
+
+  assert.match(nativeCommand, /env -i[\s\S]*LANG=en_US\.UTF-8 LC_ALL=en_US\.UTF-8/);
+});