--- a/devtools/client/inspector/test/browser_inspector_expand-collapse.js
+++ b/devtools/client/inspector/test/browser_inspector_expand-collapse.js
@@ -4,27 +4,27 @@
 
 "use strict";
 
 // Tests that context menu items exapnd all and collapse are shown properly.
 
 const TEST_URL = "data:text/html;charset=utf-8," +
                  "<div id='parent-node'><div id='child-node'></div></div>";
 
-add_task(function* () {
+add_task(async function () {
   // Test is often exceeding time-out threshold, similar to Bug 1137765
   requestLongerTimeout(2);
 
-  let {inspector} = yield openInspectorForURL(TEST_URL);
+  let {inspector} = await openInspectorForURL(TEST_URL);
 
   info("Selecting the parent node");
 
-  let front = yield getNodeFrontForSelector("#parent-node", inspector);
+  let front = await getNodeFrontForSelector("#parent-node", inspector);
 
-  yield selectNode(front, inspector);
+  await selectNode(front, inspector);
 
   info("Simulating context menu click on the selected node container.");
   let allMenuItems = openContextMenuAndGetAllItems(inspector, {
     target: getContainerForNodeFront(front, inspector).tagLine,
   });
   let nodeMenuCollapseElement =
     allMenuItems.find(item => item.id === "node-menu-collapse");
   let nodeMenuExpandElement =
@@ -32,33 +32,33 @@ add_task(function* () {
 
   ok(nodeMenuCollapseElement.disabled, "Collapse option is disabled");
   ok(!nodeMenuExpandElement.disabled, "ExpandAll option is enabled");
 
   info("Testing whether expansion works properly");
   nodeMenuExpandElement.click();
 
   info("Waiting for expansion to occur");
-  yield waitForMultipleChildrenUpdates(inspector);
+  await waitForMultipleChildrenUpdates(inspector);
   let markUpContainer = getContainerForNodeFront(front, inspector);
   ok(markUpContainer.expanded, "node has been successfully expanded");
 
   // reselecting node after expansion
-  yield selectNode(front, inspector);
+  await selectNode(front, inspector);
 
   info("Testing whether collapse works properly");
   info("Simulating context menu click on the selected node container.");
   allMenuItems = openContextMenuAndGetAllItems(inspector, {
     target: getContainerForNodeFront(front, inspector).tagLine,
   });
   nodeMenuCollapseElement =
     allMenuItems.find(item => item.id === "node-menu-collapse");
   nodeMenuExpandElement =
     allMenuItems.find(item => item.id === "node-menu-expand");
 
   ok(!nodeMenuCollapseElement.disabled, "Collapse option is enabled");
   ok(!nodeMenuExpandElement.disabled, "ExpandAll option is enabled");
   nodeMenuCollapseElement.click();
 
   info("Waiting for collapse to occur");
-  yield waitForMultipleChildrenUpdates(inspector);
+  await waitForMultipleChildrenUpdates(inspector);
   ok(!markUpContainer.expanded, "node has been successfully collapsed");
 });