diff --git a/xhtml/adopt-while-parsing-001-ref.html b/xhtml/adopt-while-parsing-001-ref.html
new file mode 100644
index 00000000000000..5b512e72f5a1f3
--- /dev/null
+++ b/xhtml/adopt-while-parsing-001-ref.html
@@ -0,0 +1,9 @@
+<!doctype html>
+<title>Test reference</title>
+<style>
+  html, body { margin: 0 }
+</style>
+<iframe src="about:blank"></iframe>
+<div>
+  PASS
+</div>
diff --git a/xhtml/adopt-while-parsing-001.html b/xhtml/adopt-while-parsing-001.html
new file mode 100644
index 00000000000000..74018b4ad0f342
--- /dev/null
+++ b/xhtml/adopt-while-parsing-001.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<title>Appending from the parser after adopting in an XML document doesn't miss notifications</title>
+<link rel="match" href="adopt-while-parsing-001-ref.html">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1511329">
+<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
+<link rel="author" title="Mozilla" href="https://mozilla.org">
+<style>
+  html, body { margin: 0 }
+</style>
+<script>
+  // If we don't get notified of the <div> insertion, the PASS text will never appear.
+  function parsingInterrupted() {
+    let frameDoc = document.querySelector("iframe").contentDocument;
+    let root = frameDoc.documentElement;
+    document.documentElement.appendChild(root);
+    root.offsetTop;
+  }
+</script>
+<iframe src="adopt-while-parsing.xhtml"></iframe>
diff --git a/xhtml/adopt-while-parsing.xhtml b/xhtml/adopt-while-parsing.xhtml
new file mode 100644
index 00000000000000..2d85d21558b177
--- /dev/null
+++ b/xhtml/adopt-while-parsing.xhtml
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml">
+<body>
+  <script>
+    window.parent.parsingInterrupted();
+  </script>
+  <div>
+    PASS
+  </div>
+</body>
+</html>
