--- a/testing/web-platform/tests/media-source/mediasource-seek-beyond-duration.html
+++ b/testing/web-platform/tests/media-source/mediasource-seek-beyond-duration.html
@@ -57,16 +57,25 @@
                     test.expectEvent(mediaElement, 'playing', 'Playing media.');
                     sourceBuffer.appendBuffer(playbackData);
                 });
 
                 test.waitForExpectedEvents(function()
                 {
                     assert_equals(mediaElement.duration, segmentInfo.duration);
                     assert_greater_than_equal(mediaElement.duration, 2.0, 'Duration is >2.0s.');
+
+                    test.expectEvent(sourceBuffer, "updateend");
+                    sourceBuffer.remove(1.5, Infinity);
+                    assert_true(sourceBuffer.updating, "updating");
+                });
+
+                test.waitForExpectedEvents(function()
+                {
+                    assert_false(sourceBuffer.updating, "updating");
                     test.waitForCurrentTimeChange(mediaElement, function()
                     {
                         // Update duration.
                         mediaSource.duration = 1.5;
                         seekToSpecifiedTimeSetEOSAndVerifyDone(test, mediaElement, mediaSource, 1.8);
                     });
                 });
             }, 'Test seeking beyond updated media duration.');