diff --git a/includes/VectorTemplate.php b/includes/VectorTemplate.php
index e13b0fc..a34b64d 100644
--- a/includes/VectorTemplate.php
+++ b/includes/VectorTemplate.php
@@ -415,10 +415,11 @@ class VectorTemplate extends BaseTemplate {
 	 */
 	private function buildNamespacesProps() : array {
 		$props = [
-			'tabs-id' => 'p-namespaces',
-			'empty-portlet' => ( count( $this->get( 'namespace_urls', [] ) ) == 0 ) ? 'emptyPortlet' : '',
+			'id' => 'p-namespaces',
+			'class' => ( count( $this->get( 'namespace_urls', [] ) ) == 0 ) ?
+				'emptyPortlet vectorTabs' : 'vectorTabs',
 			'label-id' => 'p-namespaces-label',
-			'msg-label' => $this->getMsg( 'namespaces' )->text(),
+			'label' => $this->getMsg( 'namespaces' )->text(),
 			'html-userlangattributes' => $this->get( 'userlangattributes', '' ),
 			'html-items' => '',
 		];
@@ -464,10 +465,11 @@ class VectorTemplate extends BaseTemplate {
 	 */
 	private function buildViewsProps() : array {
 		$props = [
-			'tabs-id' => 'p-views',
-			'empty-portlet' => ( count( $this->get( 'view_urls', [] ) ) == 0 ) ? 'emptyPortlet' : '',
+			'id' => 'p-views',
+			'class' => ( count( $this->get( 'view_urls', [] ) ) == 0 ) ?
+				'emptyPortlet vectorTabs' : 'vectorTabs',
 			'label-id' => 'p-views-label',
-			'msg-label' => $this->getMsg( 'views' )->text(),
+			'label' => $this->getMsg( 'views' )->text(),
 			'html-userlangattributes' => $this->get( 'userlangattributes', '' ),
 			'html-items' => '',
 		];
diff --git a/includes/templates/VectorTabs.mustache b/includes/templates/VectorTabs.mustache
index 5d5aa2e..9ff2582 100644
--- a/includes/templates/VectorTabs.mustache
+++ b/includes/templates/VectorTabs.mustache
@@ -1,13 +1,8 @@
 {{!
-	string tabs-id
-	string|null empty-portlet
-	string label-id
-	string|null msg-label
-	string|null html-userlangattributes
-	string|null html-items
+	See @typedef MenuDefinition
 }}
-<div id="{{tabs-id}}" role="navigation" class="vectorTabs {{empty-portlet}}" aria-labelledby="{{label-id}}">
-	<h3 id="{{label-id}}">{{msg-label}}</h3>
+<div id="{{id}}" role="navigation" class="{{class}}" aria-labelledby="{{label-id}}">
+	<h3 id="{{label-id}}">{{label}}</h3>
 	<ul {{{html-userlangattributes}}}>
 		{{{html-items}}}
 	</ul>
diff --git a/stories/VectorTabs.stories.data.js b/stories/VectorTabs.stories.data.js
index e681911..f0ff5bf 100644
--- a/stories/VectorTabs.stories.data.js
+++ b/stories/VectorTabs.stories.data.js
@@ -3,11 +3,14 @@ import vectorTabsTemplate from '!!raw-loader!../includes/templates/VectorTabs.mu
 
 export { vectorTabsTemplate };
 
+/**
+ * @type {MenuDefinition}
+ */
 export const pageActionsData = {
-	'tabs-id': 'p-views',
-	'empty-portlet': '',
+	id: 'p-views',
+	class: 'vectorTabs',
 	'label-id': 'p-views-label',
-	'msg-label': 'Views',
+	label: 'Views',
 	'html-userlangattributes': htmluserlangattributes,
 	'html-items': `<li id="ca-view" class="collapsible selected">
 		<a href="/wiki/Main_Page">Read</a>
@@ -22,11 +25,14 @@ You can view its source [⌃⌥e]" accesskey="e">View source</a></li>
 `
 };
 
+/**
+ * @type {MenuDefinition}
+ */
 export const namespaceTabsData = {
-	'tabs-id': 'p-namespaces',
-	'empty-portlet': '',
+	id: 'p-namespaces',
+	class: 'vectorTabs',
 	'label-id': 'p-namespaces-label',
-	'msg-label': 'Namespaces',
+	label: 'Namespaces',
 	'html-userlangattributes': htmluserlangattributes,
 	'html-items': `<li id="ca-nstab-main" class="selected"><a href="/wiki/Main_Page" title="View the content page [⌃⌥c]" accesskey="c">Main page</a></li>
 <li id="ca-talk"><a href="/wiki/Talk:Main_Page" rel="discussion" title="Discussion about the content page [⌃⌥t]" accesskey="t">Talk (3)</a></li>`
diff --git a/tests/phpunit/integration/VectorTemplateTest.php b/tests/phpunit/integration/VectorTemplateTest.php
index a0a4395..0b64f7f 100644
--- a/tests/phpunit/integration/VectorTemplateTest.php
+++ b/tests/phpunit/integration/VectorTemplateTest.php
@@ -134,6 +134,7 @@ class VectorTemplateTest extends MediaWikiIntegrationTestCase {
 	 * @covers ::buildViewsProps
 	 * @covers ::buildActionsProps
 	 * @covers ::buildVariantsProps
+	 * @covers ::buildNamespacesProps
 	 * @covers ::getMenuProps
 	 */
 	public function testGetMenuProps() {
@@ -147,17 +148,21 @@ class VectorTemplateTest extends MediaWikiIntegrationTestCase {
 
 		$props = $openVectorTemplate->getMenuProps();
 		$views = $openVectorTemplate->buildViewsProps();
+		$namespaces = $openVectorTemplate->buildNamespacesProps();
 		$this->assertSame( $views, [
-			'tabs-id' => 'p-views',
-			'empty-portlet' => 'emptyPortlet',
+			'id' => 'p-views',
+			'class' => 'emptyPortlet vectorTabs',
 			'label-id' => 'p-views-label',
-			'msg-label' => 'Views',
+			'label' => 'Views',
 			'html-userlangattributes' => $langAttrs,
 			'html-items' => '',
+			'class' => 'emptyPortlet vectorTabs',
 		] );
 
 		$variants = $openVectorTemplate->buildVariantsProps();
 		$actions = $openVectorTemplate->buildActionsProps();
+		$this->assertSame( $namespaces['class'],
+			'emptyPortlet vectorTabs' );
 		$this->assertSame( $variants['class'],
 			'emptyPortlet vectorMenu' );
 		$this->assertSame( $actions['class'],