diff --git a/includes/templates/TableOfContents__line.mustache b/includes/templates/TableOfContents__line.mustache
index 88d6e39c..09fd407d 100644
--- a/includes/templates/TableOfContents__line.mustache
+++ b/includes/templates/TableOfContents__line.mustache
@@ -1,4 +1,4 @@
-<li id="toc-{{number}}"
+<li id="toc-{{anchor}}"
 	class="sidebar-toc-list-item sidebar-toc-level-{{toclevel}}{{#is-top-level-section}}{{^vector-is-collapse-sections-enabled}} sidebar-toc-list-item-expanded{{/vector-is-collapse-sections-enabled}}{{/is-top-level-section}}">
 	<a class="sidebar-toc-link" href="#{{anchor}}">
 		<div class="sidebar-toc-text">
diff --git a/tests/jest/__snapshots__/tableOfContents.test.js.snap b/tests/jest/__snapshots__/tableOfContents.test.js.snap
index 89957bed..bd095cce 100644
--- a/tests/jest/__snapshots__/tableOfContents.test.js.snap
+++ b/tests/jest/__snapshots__/tableOfContents.test.js.snap
@@ -11,7 +11,7 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is false
 				<div class=\\"sidebar-toc-text\\">Beginning</div>
 			</a>
 		</li>
-<li id=\\"toc-1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
+<li id=\\"toc-foo\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#foo\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">1</span>foo</div>
@@ -19,20 +19,20 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is false
 	<ul class=\\"sidebar-toc-list\\">
 	</ul>
 </li>
-<li id=\\"toc-2\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
+<li id=\\"toc-bar\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#bar\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2</span>bar</div>
 	</a>
 		<button class=\\"mw-ui-icon mw-ui-icon-wikimedia-downTriangle mw-ui-icon-small sidebar-toc-toggle\\"></button>
 	<ul class=\\"sidebar-toc-list\\">
-<li id=\\"toc-2.1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-2\\">
+<li id=\\"toc-baz\\" class=\\"sidebar-toc-list-item sidebar-toc-level-2\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#baz\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2.1</span>baz</div>
 	</a>
 	<ul class=\\"sidebar-toc-list\\">
-<li id=\\"toc-2.1.1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-3\\">
+<li id=\\"toc-qux\\" class=\\"sidebar-toc-list-item sidebar-toc-level-3\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#qux\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2.1.1</span>qux</div>
@@ -44,7 +44,7 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is false
 </li>
 	</ul>
 </li>
-<li id=\\"toc-3\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
+<li id=\\"toc-quux\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1 sidebar-toc-list-item-expanded\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#quux\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">3</span>quux</div>
@@ -68,7 +68,7 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is true
 				<div class=\\"sidebar-toc-text\\">Beginning</div>
 			</a>
 		</li>
-<li id=\\"toc-1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
+<li id=\\"toc-foo\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#foo\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">1</span>foo</div>
@@ -76,20 +76,20 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is true
 	<ul class=\\"sidebar-toc-list\\">
 	</ul>
 </li>
-<li id=\\"toc-2\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
+<li id=\\"toc-bar\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#bar\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2</span>bar</div>
 	</a>
 		<button class=\\"mw-ui-icon mw-ui-icon-wikimedia-downTriangle mw-ui-icon-small sidebar-toc-toggle\\"></button>
 	<ul class=\\"sidebar-toc-list\\">
-<li id=\\"toc-2.1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-2\\">
+<li id=\\"toc-baz\\" class=\\"sidebar-toc-list-item sidebar-toc-level-2\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#baz\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2.1</span>baz</div>
 	</a>
 	<ul class=\\"sidebar-toc-list\\">
-<li id=\\"toc-2.1.1\\" class=\\"sidebar-toc-list-item sidebar-toc-level-3\\">
+<li id=\\"toc-qux\\" class=\\"sidebar-toc-list-item sidebar-toc-level-3\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#qux\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">2.1.1</span>qux</div>
@@ -101,7 +101,7 @@ exports[`Table of contents when \`vector-is-collapse-sections-enabled\` is true
 </li>
 	</ul>
 </li>
-<li id=\\"toc-3\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
+<li id=\\"toc-quux\\" class=\\"sidebar-toc-list-item sidebar-toc-level-1\\">
 	<a class=\\"sidebar-toc-link\\" href=\\"#quux\\">
 		<div class=\\"sidebar-toc-text\\">
 		<span class=\\"sidebar-toc-numb\\">3</span>quux</div>
diff --git a/tests/jest/tableOfContents.test.js b/tests/jest/tableOfContents.test.js
index bb114ab3..23b9a3e8 100644
--- a/tests/jest/tableOfContents.test.js
+++ b/tests/jest/tableOfContents.test.js
@@ -82,11 +82,11 @@ function mount( templateProps = {} ) {
 		onToggleClick
 	} );
 
-	fooSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-1' ) );
-	barSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-2' ) );
-	bazSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-2.1' ) );
-	quxSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-2.1.1' ) );
-	quuxSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-3' ) );
+	fooSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-foo' ) );
+	barSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-bar' ) );
+	bazSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-baz' ) );
+	quxSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-qux' ) );
+	quuxSection = /** @type {HTMLElement} */ ( document.getElementById( 'toc-quux' ) );
 	return toc;
 }
 
@@ -94,7 +94,7 @@ describe( 'Table of contents', () => {
 	describe( 'binds event listeners', () => {
 		test( 'for onHeadingClick', () => {
 			const toc = mount();
-			const heading = /** @type {HTMLElement} */ ( document.querySelector( `#toc-1 .${toc.LINK_CLASS}` ) );
+			const heading = /** @type {HTMLElement} */ ( document.querySelector( `#toc-foo .${toc.LINK_CLASS}` ) );
 			heading.click();
 
 			expect( onToggleClick ).not.toBeCalled();
@@ -102,7 +102,7 @@ describe( 'Table of contents', () => {
 		} );
 		test( 'for onToggleClick', () => {
 			const toc = mount();
-			const toggle = /** @type {HTMLElement} */ ( document.querySelector( `#toc-2 .${toc.TOGGLE_CLASS}` ) );
+			const toggle = /** @type {HTMLElement} */ ( document.querySelector( `#toc-bar .${toc.TOGGLE_CLASS}` ) );
 			toggle.click();
 
 			expect( onHeadingClick ).not.toBeCalled();
@@ -122,28 +122,28 @@ describe( 'Table of contents', () => {
 	describe( 'when changing sections', () => {
 		test( 'applies correct class', () => {
 			const toc = mount( { 'vector-is-collapse-sections-enabled': true } );
-			toc.changeActiveSection( 'toc-1' );
+			toc.changeActiveSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( true );
 			expect( barSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( bazSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( quxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( quuxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 
-			toc.changeActiveSection( 'toc-2' );
+			toc.changeActiveSection( 'toc-bar' );
 			expect( fooSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( barSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( quxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( quuxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 
-			toc.changeActiveSection( 'toc-2.1' );
+			toc.changeActiveSection( 'toc-baz' );
 			expect( fooSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( barSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( true );
 			expect( quxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( quuxSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 
-			toc.changeActiveSection( 'toc-2.1.1' );
+			toc.changeActiveSection( 'toc-qux' );
 			expect( fooSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
 			expect( barSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.ACTIVE_SECTION_CLASS ) ).toEqual( false );
@@ -160,14 +160,14 @@ describe( 'Table of contents', () => {
 
 		test( 'expands sections', () => {
 			const toc = mount();
-			toc.expandSection( 'toc-1' );
+			toc.expandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( barSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 			expect( quxSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 			expect( quuxSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 
-			toc.expandSection( 'toc-2' );
+			toc.expandSection( 'toc-bar' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( barSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
@@ -177,10 +177,10 @@ describe( 'Table of contents', () => {
 
 		test( 'toggles expanded sections', () => {
 			const toc = mount();
-			toc.toggleExpandSection( 'toc-1' );
+			toc.toggleExpandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 
-			toc.toggleExpandSection( 'toc-1' );
+			toc.toggleExpandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 		} );
 	} );
@@ -193,14 +193,14 @@ describe( 'Table of contents', () => {
 
 		test( 'expands sections', () => {
 			const toc = mount( { 'vector-is-collapse-sections-enabled': true } );
-			toc.expandSection( 'toc-1' );
+			toc.expandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( barSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 			expect( bazSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 			expect( quxSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 			expect( quuxSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 
-			toc.expandSection( 'toc-2' );
+			toc.expandSection( 'toc-bar' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( barSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 			expect( bazSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
@@ -210,10 +210,10 @@ describe( 'Table of contents', () => {
 
 		test( 'toggles expanded sections', () => {
 			const toc = mount( { 'vector-is-collapse-sections-enabled': true } );
-			toc.toggleExpandSection( 'toc-1' );
+			toc.toggleExpandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( true );
 
-			toc.toggleExpandSection( 'toc-1' );
+			toc.toggleExpandSection( 'toc-foo' );
 			expect( fooSection.classList.contains( toc.EXPANDED_SECTION_CLASS ) ).toEqual( false );
 		} );