--- a/testing/web-platform/tests/web-animations/animation-model/keyframe-effects/effect-value-context.html
+++ b/testing/web-platform/tests/web-animations/animation-model/keyframe-effects/effect-value-context.html
@@ -77,10 +77,28 @@ promise_test(function(t) {
     assert_equals(getComputedStyle(div).marginLeft, '150px',
                   'Effect value after attaching to font-size:10px parent');
     divWith20pxFontSize.appendChild(div);
     assert_equals(getComputedStyle(div).marginLeft, '300px',
                   'Effect value after attaching to font-size:20px parent');
   });
 }, 'Effect values reflect changes to font-size from reparenting');
 
+test(function(t) {
+  var divA = createDiv(t);
+  divA.style.fontSize = '10px';
+
+  var divB = createDiv(t);
+  divB.style.fontSize = '20px';
+
+  var animation = divA.animate([ { marginLeft: '10em' },
+                                 { marginLeft: '20em' } ], 1000);
+  animation.currentTime = 500;
+  assert_equals(getComputedStyle(divA).marginLeft, '150px',
+                'Effect value before updating target element');
+
+  animation.effect.target = divB;
+  assert_equals(getComputedStyle(divB).marginLeft, '300px',
+                'Effect value after updating target element');
+}, 'Effect values reflect changes to target element');
+
 </script>
 </body>