diff --git a/.github/workflows/build_and_publish.yaml b/.github/workflows/build_and_publish.yaml
index 234eb14..470003f 100644
--- a/.github/workflows/build_and_publish.yaml
+++ b/.github/workflows/build_and_publish.yaml
@@ -28,6 +28,14 @@ jobs:
       - name: Build the project
         run: npm run build
 
+      # The guard's own regression cases, so a refactor that silently stops catching names fails here.
+      - name: Test the brand guard
+        run: node scripts/check-brand-package.test.mjs
+
+      # Runs on pull requests too, so a branded name is caught before it can be merged and published.
+      - name: Assert the package carries no company name
+        run: node scripts/check-brand-package.mjs
+
       - name: Publish to npm
         if: github.event_name == 'push' && github.ref == 'refs/heads/master'
         run: npm publish
diff --git a/CHANGES.md b/CHANGES.md
index c9a51a5..6b6e349 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,9 @@
+### 1.3.5
+- Build guard: also catches the spaced and hyphenated spellings of each company name, for example `Payment IQ` or `payment-iq`
+
+### 1.3.4
+- Build guard: the published package is scanned for company names before `npm publish`, and the guard has its own regression cases. No change to shipped code; `dist` and `index.d.ts` are byte-identical to 1.3.3
+
 ### 1.3.3
 - Origin validation now accepts messages only from the origin of the configured `hostedfieldsurl`. The two built-in fallback origins are removed, so `hostedfieldsurl` must point at the host the iframes actually load from
 - Remove repository, author and brand keywords from package metadata, and publish only `dist` and `index.d.ts`
diff --git a/package-lock.json b/package-lock.json
index 785bda1..87fea1b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "hosted-fields-sdk",
-  "version": "1.3.3",
+  "version": "1.3.5",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "hosted-fields-sdk",
-      "version": "1.3.3",
+      "version": "1.3.5",
       "license": "ISC",
       "dependencies": {
         "@babel/runtime": "^7.27.0"
diff --git a/package.json b/package.json
index 2330d7a..66151cd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "hosted-fields-sdk",
-  "version": "1.3.3",
+  "version": "1.3.5",
   "description": "Hosted fields sdk",
   "main": "dist/index.js",
   "types": "index.d.ts",
@@ -24,7 +24,9 @@
     "build": "rimraf dist && npm run eslint && npm run build:cjs && npm run build:esm && npm run uglify",
     "build:cjs": "babel src --out-dir dist --env-name cjs",
     "uglify": "recursive-uglifyjs dist",
-    "build:esm": "babel src --out-dir dist/esm --extensions '.js' --env-name esm"
+    "build:esm": "babel src --out-dir dist/esm --extensions '.js' --env-name esm",
+    "check:brand": "node scripts/check-brand-package.mjs",
+    "check:brand:test": "node scripts/check-brand-package.test.mjs"
   },
   "devDependencies": {
     "@babel/cli": "^7.26.4",
diff --git a/scripts/check-brand-package.mjs b/scripts/check-brand-package.mjs
new file mode 100644
index 0000000..4cd5925
--- /dev/null
+++ b/scripts/check-brand-package.mjs
@@ -0,0 +1,91 @@
+/*
+  Asserts the published package carries no company name (PIQ-5877).
+
+  Scans what `npm pack` would ship rather than the working tree: `files` limits the tarball to dist
+  and index.d.ts, so CHANGES.md and .github never ship and scanning the tree would fail on their
+  GitHub links for no reason. CI publishes on every push to master, so this runs before `npm publish`
+  and on pull requests: a name that reaches npm cannot be withdrawn, only superseded.
+
+  Deliberately not configurable from the environment. A guard that can be switched off where it runs
+  is not a guard.
+*/
+import { execFileSync } from 'child_process';
+import { readFileSync } from 'fs';
+
+/*
+  Former and current company names, plus the two paymentiq.io tenants, each split where a human would
+  space it. Matching the closed-up spelling alone lets the prose form through: `Payment IQ` in a
+  README, `Mr Green` in a comment, `payment-iq` in a filename. The repo already writes it both ways,
+  for example `// The payment iq mid` in src/sdk/api/index.js.
+*/
+const FORBIDDEN = [
+  ['payment', 'iq'],
+  ['world', 'line'],
+  ['dev', 'code'],
+  ['bambora'],
+  ['casumo'],
+  ['mr', 'green'],
+];
+
+// Whitespace, underscore, dot or hyphen between the parts, in any number, including none.
+const SEPARATOR = '[\\s_.-]*';
+
+// Word characters only, so joining the parts into an alternation cannot introduce a metacharacter.
+const malformed = FORBIDDEN.flat().filter((part) => !/^\w+$/.test(part));
+if (malformed.length) {
+  console.error(`FORBIDDEN parts must be word characters only: ${malformed.join(', ')}`);
+  process.exit(2);
+}
+
+const names = FORBIDDEN.map((parts) => parts.join(''));
+
+let files;
+try {
+  // --dry-run writes nothing; the JSON lists exactly what a real pack would include.
+  const out = execFileSync('npm', ['pack', '--dry-run', '--json'], { encoding: 'utf-8' });
+  files = JSON.parse(out)[0].files.map((f) => f.path);
+} catch (error) {
+  console.error(`Could not read the package contents: ${error.message}`);
+  process.exit(2);
+}
+
+if (!files.length) {
+  console.error('npm pack listed no files, which cannot be right');
+  process.exit(2);
+}
+
+const pattern = new RegExp(FORBIDDEN.map((parts) => parts.join(SEPARATOR)).join('|'), 'gi');
+const failures = [];
+
+for (const file of files) {
+  let contents;
+  try {
+    contents = readFileSync(file, 'utf-8');
+  } catch (error) {
+    // A file that ships but cannot be read is a hole in the guard, not something to skip.
+    console.error(`Could not read ${file}: ${error.message}`);
+    process.exit(2);
+  }
+  // The packed path counts as well as the contents: it becomes the consumer's import path, so
+  // `dist/paymentiq.js` carries the name whatever the file says. Relative, as npm lists it, since
+  // the absolute path runs through a checkout directory nobody chose.
+  const hits = [...(file.match(pattern) ?? []), ...(contents.match(pattern) ?? [])];
+  if (hits.length) failures.push({ file, hits });
+}
+
+if (failures.length) {
+  console.error(`The published package carries a company name, in ${failures.length} file(s):\n`);
+  for (const { file, hits } of failures) {
+    const counts = new Map();
+    for (const hit of hits) {
+      const name = hit.toLowerCase();
+      counts.set(name, (counts.get(name) ?? 0) + 1);
+    }
+    const summary = [...counts].map(([name, n]) => `${name} x${n}`).join(', ');
+    console.error(`  ${file}: ${summary}`);
+  }
+  console.error(`\nScanned ${files.length} packed file(s) for: ${names.join(', ')}, spaced or hyphenated too`);
+  process.exit(1);
+}
+
+console.log(`No company name in any of the ${files.length} packed file(s).`);
diff --git a/scripts/check-brand-package.test.mjs b/scripts/check-brand-package.test.mjs
new file mode 100644
index 0000000..ce5a9fb
--- /dev/null
+++ b/scripts/check-brand-package.test.mjs
@@ -0,0 +1,94 @@
+/*
+  Proves the guard fails a seeded regression (PIQ-5877, AC 1).
+
+  Usage: node scripts/check-brand-package.test.mjs
+
+  Each fixture is a real package directory the guard runs in, because the guard reads `npm pack`
+  rather than the tree: a fixture that only wrote files would not exercise the thing that decides
+  what ships, which is `files` in package.json.
+
+  Runs the real script and asserts its exit code, since that is what the CI step acts on.
+
+  No test runner, deliberately. `npm test` here is a placeholder, and adding a framework to assert
+  exit codes would be more moving parts than the thing it checks.
+*/
+import { execFileSync } from 'child_process';
+import { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'fs';
+import { tmpdir } from 'os';
+import { join, dirname, resolve } from 'path';
+import { fileURLToPath } from 'url';
+
+const guard = resolve(dirname(fileURLToPath(import.meta.url)), 'check-brand-package.mjs');
+
+/** The guard's exit code in a fixture package: 0 clean, 1 a name found, 2 misconfigured. */
+const run = (dir) => {
+  try {
+    execFileSync('node', [guard], { cwd: dir, encoding: 'utf-8', stdio: 'pipe' });
+    return 0;
+  } catch (error) {
+    return error.status;
+  }
+};
+
+const fixture = (files, pkg = {}) => {
+  const dir = mkdtempSync(join(tmpdir(), 'brand-guard-'));
+  writeFileSync(
+    join(dir, 'package.json'),
+    JSON.stringify({ name: 'fixture', version: '1.0.0', ...pkg }, null, 2),
+  );
+  for (const [name, body] of Object.entries(files)) {
+    mkdirSync(dirname(join(dir, name)), { recursive: true });
+    writeFileSync(join(dir, name), body);
+  }
+  return dir;
+};
+
+const SHIPS_DIST = { files: ['dist'] };
+
+const cases = [
+  ['a clean package passes', { 'dist/index.js': 'var a=1' }, SHIPS_DIST, 0],
+  ['a company name in a shipped file fails', { 'dist/index.js': 'var a="paymentiq"' }, SHIPS_DIST, 1],
+  ['a former company name fails', { 'dist/index.js': '/* bambora */' }, SHIPS_DIST, 1],
+  ['a tenant name fails', { 'dist/index.js': 'mrgreen' }, SHIPS_DIST, 1],
+  // Copilot raised this: the packed path becomes the consumer's import path.
+  ['a company name in the packed path fails', { 'dist/paymentiq.js': 'var a=1' }, SHIPS_DIST, 1],
+  ['case is ignored', { 'dist/index.js': 'PaymentIQ' }, SHIPS_DIST, 1],
+  // Ross on #48: matching only the closed-up spelling let the prose form through.
+  ['a spaced company name fails', { 'dist/index.js': '// The payment iq mid' }, SHIPS_DIST, 1],
+  ['a hyphenated company name fails', { 'dist/index.js': 'payment-iq' }, SHIPS_DIST, 1],
+  ['a spaced tenant name fails', { 'dist/index.js': 'Powered by Mr Green' }, SHIPS_DIST, 1],
+  ['a dotted company name fails', { 'dist/index.js': 'world.line' }, SHIPS_DIST, 1],
+  ['a spaced name in the packed path fails', { 'dist/payment-iq.js': 'var a=1' }, SHIPS_DIST, 1],
+  // The point of scanning `npm pack` rather than the tree: `files` decides what ships.
+  [
+    'a name in a file that does not ship passes',
+    { 'dist/index.js': 'var a=1', 'CHANGES.md': 'github.com/devcode-git/x' },
+    SHIPS_DIST,
+    0,
+  ],
+  [
+    'the same name fails once that file ships',
+    { 'dist/index.js': 'var a=1', 'CHANGES.md': 'github.com/devcode-git/x' },
+    { files: ['dist', 'CHANGES.md'] },
+    1,
+  ],
+];
+
+let failed = 0;
+for (const [name, files, pkg, expected] of cases) {
+  const dir = fixture(files, pkg);
+  const actual = run(dir);
+  rmSync(dir, { recursive: true, force: true });
+  if (actual === expected) {
+    console.log(`  ok    ${name}`);
+  } else {
+    console.error(`  FAIL  ${name}: expected exit ${expected}, got ${actual}`);
+    failed += 1;
+  }
+}
+
+if (failed) {
+  console.error(`\n${failed} case(s) failed.`);
+  process.exit(1);
+}
+console.log(`\nAll ${cases.length} cases passed.`);