1 files changed, 2 insertions, 1 deletions
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
index 42828308d7..13cdefb5d3 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-window-open.html
@@ -21,7 +21,8 @@ async_test(t => {
       assert_equals(e.destination.id, "");
       assert_equals(e.destination.index, -1);
       assert_equals(e.formData, null);
-      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);
       e.preventDefault();
     });