--- a/devtools/client/inspector/computed/test/browser_computed_refresh-on-style-change_01.js
+++ b/devtools/client/inspector/computed/test/browser_computed_refresh-on-style-change_01.js
@@ -4,28 +4,27 @@
 
 "use strict";
 
 // Tests that the computed view refreshes when the current node has its style
 // changed.
 
 const TEST_URI = "<div id='testdiv' style='font-size:10px;'>Test div!</div>";
 
-add_task(function*() {
+add_task(function* () {
   yield addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
-  let {inspector, view} = yield openComputedView();
+  let {inspector, view, testActor} = yield openComputedView();
   yield selectNode("#testdiv", inspector);
 
   let fontSize = getComputedViewPropertyValue(view, "font-size");
   is(fontSize, "10px", "The computed view shows the right font-size");
 
   info("Changing the node's style and waiting for the update");
   let onUpdated = inspector.once("computed-view-refreshed");
-  // FIXME: use the testActor to set style on the node.
-  content.document.querySelector("#testdiv")
-                  .style.cssText = "font-size: 15px; color: red;";
+  yield testActor.setAttribute("#testdiv", "style",
+                               "font-size: 15px; color: red;");
   yield onUpdated;
 
   fontSize = getComputedViewPropertyValue(view, "font-size");
   is(fontSize, "15px", "The computed view shows the updated font-size");
   let color = getComputedViewPropertyValue(view, "color");
   is(color, "rgb(255, 0, 0)", "The computed view also shows the color now");
 });