diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index 90d74745236..24d4a7ee7da 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -331418,6 +331418,12 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html",
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-iframe-element/cross_origin_parentage.html": [
     [
      "/html/semantics/embedded-content/the-iframe-element/cross_origin_parentage.html",
@@ -570683,6 +570689,10 @@
    "56df0cb79a1af927a0209c0bbbb5edb25ccaee5f",
    "testharness"
   ],
+  "html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html": [
+   "46708fc218e559fba7049a36888a7c8a24c22672",
+   "testharness"
+  ],
   "html/semantics/embedded-content/the-iframe-element/cross_origin_child.html": [
    "a42082bb612b280eda5aa598ed750cfce3edd537",
    "support"
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html
new file mode 100644
index 00000000000..2cb85700230
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html
@@ -0,0 +1,21 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Iframe's contentDocument should only change after its pending load has matured.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body></body>
+<script>
+async_test(function(t) {
+    var iframe = document.createElement("iframe");
+    document.body.appendChild(iframe);
+    iframe.onload = t.step_func(function() {
+        assert_true(iframe.contentDocument.location.toString().includes("support/blank.htm"));
+        t.done();
+    });
+
+    assert_equals(iframe.contentDocument.location.toString(), "about:blank");
+    iframe.src = "support/blank.htm?pipe=trickle(d2)";
+    // The location of the contentDocument should not change until the new document has matured.
+    assert_equals(iframe.contentDocument.location.toString(), "about:blank");
+}, "contentDocument should only change after a load matures.");
+</script>
