diff --git a/extension/devtools/devtools.js b/extension/devtools/devtools.js
index cebb52534..00450e611 100644
--- a/extension/devtools/devtools.js
+++ b/extension/devtools/devtools.js
@@ -8,13 +8,13 @@
 
 chrome.devtools.panels.create(
   'Impeccable',
-  'icons/icon-32.png',
-  'devtools/panel.html'
+  '/icons/icon-32.png',
+  '/devtools/panel.html'
 );
 
 // Sidebar pane in the Elements panel: shows findings for the currently selected element
 chrome.devtools.panels.elements.createSidebarPane('Impeccable', (sidebar) => {
-  sidebar.setPage('devtools/sidebar.html');
+  sidebar.setPage('/devtools/sidebar.html');
   sidebar.setHeight('200px');
 });
 
diff --git a/scripts/test-suites.mjs b/scripts/test-suites.mjs
index 134093030..68205a0fd 100644
--- a/scripts/test-suites.mjs
+++ b/scripts/test-suites.mjs
@@ -68,7 +68,7 @@ export const SUITES = {
       /^extension\/(background|content|detector|devtools|popup|manifest\.json)/,
       /^scripts\/(benchmark-detector|build-browser-detector|build-extension)\.js$/,
       /^site\/(pages\/detector|public\/antipattern|data\/anti-patterns-catalog\.js)/,
-      /^tests\/(detect-antipatterns|fixtures\/antipatterns)/,
+      /^tests\/(detect-antipatterns|extension-build|fixtures\/antipatterns)/,
     ],
     commands: [
       {
@@ -81,6 +81,7 @@ export const SUITES = {
       {
         runner: 'node',
         files: [
+          'tests/extension-build.test.mjs',
           'tests/detect-antipatterns-fixtures.test.mjs',
           'tests/detect-antipatterns-browser.test.mjs',
         ],
diff --git a/tests/extension-build.test.mjs b/tests/extension-build.test.mjs
new file mode 100644
index 000000000..53d7243c8
--- /dev/null
+++ b/tests/extension-build.test.mjs
@@ -0,0 +1,22 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+
+const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+
+describe('extension DevTools packaging', () => {
+  it('uses extension-root paths for DevTools panel pages', () => {
+    const source = readFileSync(path.join(ROOT, 'extension/devtools/devtools.js'), 'utf-8');
+
+    assert.match(
+      source,
+      /chrome\.devtools\.panels\.create\(\s*['"]Impeccable['"],\s*['"]\/icons\/icon-32\.png['"],\s*['"]\/devtools\/panel\.html['"]\s*\)/s,
+      'Firefox resolves DevTools URLs relative to devtools.html unless they start at the extension root',
+    );
+    assert.match(source, /sidebar\.setPage\(['"]\/devtools\/sidebar\.html['"]\)/);
+    assert.doesNotMatch(source, /['"]devtools\/(?:panel|sidebar)\.html['"]/);
+    assert.doesNotMatch(source, /['"]icons\/icon-32\.png['"]/);
+  });
+});