1 files changed, 2 insertions, 1 deletions
diff --git a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
index 9da4ddcd50..4529fe25ac 100644
--- a/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
+++ b/testing/web-platform/tests/navigation-api/navigate-event/navigate-history-back-after-fragment.html
@@ -24,7 +24,8 @@ async_test(t => {
       assert_equals(e.destination.id, target_id);
         assert_equals(e.destination.index, start_index);
       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);
     });
 
     history.back();