diff --git a/element-timing/observe-shadow-image.html b/element-timing/observe-shadow-image.html
index 4309196cddcdca..12bda4724bd8bf 100644
--- a/element-timing/observe-shadow-image.html
+++ b/element-timing/observe-shadow-image.html
@@ -1,6 +1,6 @@
 <!DOCTYPE HTML>
 <meta charset=utf-8>
-<title>Element Timing: observe image in shadow tree</title>
+<title>Element Timing: do not observe image in shadow tree</title>
 <style>
 body {
   margin: 0;
@@ -19,13 +19,7 @@
     }
     const observer = new PerformanceObserver(
       t.step_func_done(function(entryList) {
-        assert_equals(entryList.getEntries().length, 1);
-        const entry = entryList.getEntries()[0];
-        const pathname = window.location.origin + '/element-timing/resources/square100.png';
-        checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img);
-        // Assume viewport has size at least 100, so the element is fully visible.
-        checkRect(entry, [0, 100, 0, 100]);
-        checkNaturalSize(entry, 100, 100);
+        assert_unreached('Should not observe elements in shadow trees!');
       })
     );
     observer.observe({entryTypes: ['element']});
@@ -40,6 +34,10 @@
       const shadowRoot = document.getElementById('target').attachShadow({mode: 'closed'});
       shadowRoot.appendChild(img);
       beforeRender = performance.now();
+      t.step_timeout(() => {
+        // Assume entry was not dispatched, so test passes.
+        t.done();
+      }, 500);
     };
-  }, 'Image in shadow tree with elementtiming attribute is observable.');
+  }, 'Image in shadow tree with elementtiming attribute is not observable.');
 </script>
