diff --git a/src/mock-doc/serialize-node.ts b/src/mock-doc/serialize-node.ts
index c77c019a835..ee75ed901cb 100644
--- a/src/mock-doc/serialize-node.ts
+++ b/src/mock-doc/serialize-node.ts
@@ -474,6 +474,7 @@ function isWithinWhitespaceSensitive(node: Node) {
   return false;
 }
 
+// TODO(STENCIL-1299): Audit this list, remove unsupported/deprecated elements
 /*@__PURE__*/ export const NON_ESCAPABLE_CONTENT = new Set([
   'STYLE',
   'SCRIPT',
@@ -485,6 +486,7 @@ function isWithinWhitespaceSensitive(node: Node) {
   'PLAINTEXT',
 ]);
 
+// TODO(STENCIL-1299): Audit this list, remove unsupported/deprecated elements
 /**
  * A list of whitespace sensitive tag names, such as `code`, `pre`, etc.
  */
@@ -498,7 +500,8 @@ function isWithinWhitespaceSensitive(node: Node) {
   'TEXTAREA',
 ]);
 
-/*@__PURE__*/ const EMPTY_ELEMENTS = new Set([
+// TODO(STENCIL-1299): Audit this list, remove unsupported/deprecated elements
+/*@__PURE__*/ export const EMPTY_ELEMENTS = new Set([
   'area',
   'base',
   'basefont',
@@ -516,11 +519,14 @@ function isWithinWhitespaceSensitive(node: Node) {
   'param',
   'source',
   'trace',
+  'track',
   'wbr',
 ]);
 
+// TODO(STENCIL-1299): Audit this list, remove unsupported/deprecated attr
 /*@__PURE__*/ const REMOVE_EMPTY_ATTR = new Set(['class', 'dir', 'id', 'lang', 'name', 'title']);
 
+// TODO(STENCIL-1299): Audit this list, remove unsupported/deprecated attr
 /*@__PURE__*/ const BOOLEAN_ATTR = new Set([
   'allowfullscreen',
   'async',
diff --git a/src/mock-doc/test/serialize-node.spec.ts b/src/mock-doc/test/serialize-node.spec.ts
index 32008092fdb..e04efdb3817 100644
--- a/src/mock-doc/test/serialize-node.spec.ts
+++ b/src/mock-doc/test/serialize-node.spec.ts
@@ -1,5 +1,5 @@
 import { MockDocument } from '../document';
-import { serializeNodeToHtml } from '../serialize-node';
+import { EMPTY_ELEMENTS, serializeNodeToHtml } from '../serialize-node';
 
 describe('serializeNodeToHtml', () => {
   let doc: MockDocument;
@@ -278,4 +278,19 @@ describe('serializeNodeToHtml', () => {
     scriptElm.innerHTML = input;
     expect(scriptElm.innerHTML).toBe(input);
   });
+
+  it.each([...EMPTY_ELEMENTS])("does not add a closing tag for '%s'", (voidElm) => {
+    if (voidElm === 'frame') {
+      // 'frame' is a non-HTML5 compatible/deprecated element.
+      // Stencil technically still supports it, but it doesn't get rendered as a child element, so let's just skip it
+      return;
+    }
+
+    const elm = doc.createElement('div');
+
+    elm.innerHTML = `<${voidElm}>`;
+
+    const html = serializeNodeToHtml(elm, { prettyHtml: true });
+    expect(html).toBe(`<${voidElm}>`);
+  });
 });