--- a/browser/components/extensions/test/browser/browser_ext_runtime_setUninstallURL.js
+++ b/browser/components/extensions/test/browser/browser_ext_runtime_setUninstallURL.js
@@ -1,39 +1,27 @@
 "use strict";
 
 let {AddonManager} = Components.utils.import("resource://gre/modules/AddonManager.jsm", {});
 let {Extension} = Components.utils.import("resource://gre/modules/Extension.jsm", {});
 
-function install(url) {
-  return new Promise((resolve, reject) => {
-    AddonManager.getInstallForURL(url, (install) => {
-      install.addListener({
-        onInstallEnded: (i, addon) => resolve(addon),
-        onInstallFailed: () => reject(),
-      });
-      install.install();
-    }, "application/x-xpinstall");
-  });
-}
-
 function* makeAndInstallXPI(id, backgroundScript, loadedURL) {
   let xpi = Extension.generateXPI(id, {
     background: "(" + backgroundScript.toString() + ")()",
   });
   SimpleTest.registerCleanupFunction(function cleanupXPI() {
     Services.obs.notifyObservers(xpi, "flush-cache-entry", null);
     xpi.remove(false);
   });
 
   let loadPromise = BrowserTestUtils.waitForNewTab(gBrowser, loadedURL);
 
-  let fileURI = Services.io.newFileURI(xpi);
-  info(`installing ${fileURI.spec}`);
-  let addon = yield install(fileURI.spec);
+
+  info(`installing ${xpi.path}`);
+  let addon = yield AddonManager.installTemporaryAddon(xpi);
   info("installed");
 
   // A WebExtension is started asynchronously, we have our test extension
   // open a new tab to signal that the background script has executed.
   let loadTab = yield loadPromise;
   yield BrowserTestUtils.removeTab(loadTab);
 
   return addon;

--- a/toolkit/mozapps/extensions/internal/XPIProvider.jsm
+++ b/toolkit/mozapps/extensions/internal/XPIProvider.jsm
@@ -3871,16 +3871,18 @@ this.XPIProvider = {
                                            false);
     XPIProvider.callBootstrapMethod(addon, file, "startup",
                                     BOOTSTRAP_REASONS.ADDON_ENABLE);
     AddonManagerPrivate.callInstallListeners("onExternalInstall",
                                              null, addon.wrapper,
                                              oldAddon ? oldAddon.wrapper : null,
                                              false);
     AddonManagerPrivate.callAddonListeners("onInstalled", addon.wrapper);
+
+    return addon.wrapper;
   }),
 
   /**
    * Returns an Addon corresponding to an instance ID.
    * @param aInstanceID
    *        An Addon Instance ID
    * @return {Promise}
    * @resolves The found Addon or null if no such add-on exists.