--- a/toolkit/mozapps/update/tests/chrome/test_9999_cleanup.xul
+++ b/toolkit/mozapps/update/tests/chrome/test_9999_cleanup.xul
@@ -62,31 +62,32 @@ function runTest() {
   file = dir.clone();
   file.append(FILE_UPDATE_STATUS);
   ok(!file.exists(), file.path + " should not exist");
 
   file = dir.clone();
   file.append(FILE_UPDATE_ARCHIVE);
   ok(!file.exists(), file.path + " should not exist");
 
-  let addonPrepDir = Services.dirsvc.get(NS_APP_USER_PROFILE_50_DIR,
-                                         Ci.nsILocalFile);
-  addonPrepDir.append(ADDON_PREP_DIR);
-  // Not being able to remove the directory used to create the test add-ons
-  // will not adversely affect subsequent tests so wrap it in a try block and
-  // don't test whether its removal was successful.
-  try {
-    removeDirRecursive(addonPrepDir);
-  }
-  catch (e) {
-    logTestInfo("Unable to remove directory. Path: " + addonPrepDir.path +
-                ", Exception: " + e);
-  }
-
-  resetAddons(cleanupRestoreUpdaterBackup);
+  resetAddons(() => {
+    let addonPrepDir = Services.dirsvc.get(NS_APP_USER_PROFILE_50_DIR,
+                                           Ci.nsILocalFile);
+    addonPrepDir.append(ADDON_PREP_DIR);
+    // Not being able to remove the directory used to create the test add-ons
+    // will not adversely affect subsequent tests so wrap it in a try block and
+    // don't test whether its removal was successful.
+    try {
+      removeDirRecursive(addonPrepDir);
+    }
+    catch (e) {
+      logTestInfo("Unable to remove directory. Path: " + addonPrepDir.path +
+                  ", Exception: " + e);
+    }
+    cleanupRestoreUpdaterBackup();
+  });
 }
 
 /**
  * After all tests finish this will repeatedly attempt to restore the real
  * updater if it exists and then call finishTest after the restore is
  * successful.
  */
 function cleanupRestoreUpdaterBackup() {

--- a/toolkit/mozapps/update/tests/chrome/utils.js
+++ b/toolkit/mozapps/update/tests/chrome/utils.js
@@ -1311,55 +1311,24 @@ function setupAddons(aCallback) {
         aAddon.userDisabled = true;
       }
     });
     // If there are no pre-existing add-ons the preference value will be an
     // empty string.
     Services.prefs.setCharPref(PREF_DISABLEDADDONS, disabledAddons.join(" "));
 
     // Install the test add-ons.
-    let xpiFiles = getTestAddonXPIFiles();
-    let xpiCount = xpiFiles.length;
-    let installs = [];
-    xpiFiles.forEach(function(aFile) {
-      AddonManager.getInstallForFile(aFile, function(aInstall) {
-        if (!aInstall) {
-          throw "No AddonInstall created for " + aFile.path;
-        }
-
-        installs.push(aInstall);
-
-        if (--xpiCount == 0) {
-          let installCount = installs.length;
-          let installCompleted = function(aInstall) {
-            aInstall.removeListener(listener);
-
-            if (getAddonTestType(aInstall.addon.name) == "userdisabled") {
-              aInstall.addon.userDisabled = true;
-            }
-            if (--installCount == 0) {
-              setNoUpdateAddonsDisabledState();
-            }
-          };
-
-          let listener = {
-            onDownloadFailed: installCompleted,
-            onDownloadCancelled: installCompleted,
-            onInstallFailed: installCompleted,
-            onInstallCancelled: installCompleted,
-            onInstallEnded: installCompleted
-          };
-
-          installs.forEach(function(aInstall) {
-            aInstall.addListener(listener);
-            aInstall.install();
-          });
+    let promises = getTestAddonXPIFiles().map(function(aFile) {
+      return AddonManager.installTemporaryAddon(aFile).then(addon => {
+        if (getAddonTestType(addon.name) == "userdisabled") {
+          addon.userDisabled = true;
         }
       });
     });
+    return Promise.all(promises).then(setNoUpdateAddonsDisabledState);
   });
 }
 
 /**
  * Uninstalls the test add-ons, enables add-ons that were disabled when the
  * test started, and calls the callback specified in the aCallback parameter.
  *
  * @param  aCallback