1 files changed, 2 insertions, 1 deletions
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document-in-iframe.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document-in-iframe.html
index 42c694e290..3d810d2f1d 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document-in-iframe.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-navigation-back-same-document-in-iframe.html
@@ -27,7 +27,8 @@ promise_test(async t => {
     assert_equals(e.destination.index, 0);
     assert_equals(e.formData, null);
     assert_equals(e.info, "hi");
-    assert_equals(e.sourceElement, null);
+    // NavigateEvent sourceElement is still in development, so test whether it is available.
+    if ("sourceElement" in e) assert_equals(e.sourceElement, null);
   }
   await i.contentWindow.navigation.back({ info: "hi" }).finished;
 }, "navigate event for navigation.back() - same-document in an iframe");