--- a/dom/animation/test/chrome/test_running_on_compositor.html
+++ b/dom/animation/test/chrome/test_running_on_compositor.html
@@ -726,17 +726,17 @@ promise_test(function(t) {
   });
 }, 'Transitions override important rules');
 
 promise_test(function(t) {
   var div = addDiv(t, { style: 'transition: opacity 100s; ' +
                                'opacity: 0 !important' });
   getComputedStyle(div).opacity;
 
-  div.animate({ opacity: [ 0, 1 ] }, 10 * MS_PER_SEC);
+  div.animate({ opacity: [ 0, 1 ] }, 100 * MS_PER_SEC);
 
   div.style.setProperty('opacity', '1', 'important');
   getComputedStyle(div).opacity;
 
   var [transition, animation] = div.getAnimations();
 
   return Promise.all([transition.ready, animation.ready]).then(function() {
     assert_animation_is_not_running_on_compositor(transition,