--- a/testing/mochitest/jetpack-addon-harness.js
+++ b/testing/mochitest/jetpack-addon-harness.js
@@ -4,17 +4,16 @@ var gConfig;
 if (Cc === undefined) {
   var Cc = Components.classes;
   var Ci = Components.interfaces;
   var Cu = Components.utils;
 }
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
-Cu.import("resource://gre/modules/Timer.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "Services",
   "resource://gre/modules/Services.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "AddonManager",
   "resource://gre/modules/AddonManager.jsm");
 
 setTimeout(testInit, 0);
 
@@ -93,25 +92,32 @@ function installAddon(url) {
 // Uninstalls an add-on returning a promise for when it is gone
 function uninstallAddon(oldAddon) {
   return new Promise(function(resolve, reject) {
     AddonManager.addAddonListener({
       onUninstalled: function(addon) {
         if (addon.id != oldAddon.id)
           return;
 
+        AddonManager.removeAddonListener(this);
+
         dump("TEST-INFO | jetpack-addon-harness.js | Uninstalled test add-on " + addon.id + "\n");
 
         // Some add-ons do async work on uninstall, we must wait for that to
         // complete
         setTimeout(resolve, 500);
       }
     });
 
     oldAddon.uninstall();
+
+    // The uninstall should happen quickly, if not throw an exception
+    setTimeout(() => {
+      reject(new Error(`Addon ${oldAddon.id} failed to uninstall in a timely fashion.`));
+    }, 10000);
   });
 }
 
 // Waits for a test add-on to signal it has completed its tests
 function waitForResults() {
   return new Promise(function(resolve, reject) {
     Services.obs.addObserver(function(subject, topic, data) {
       Services.obs.removeObserver(arguments.callee, "sdk:test:results");