--- a/browser/devtools/tilt/test/browser_tilt_02_notifications-seq.js
+++ b/browser/devtools/tilt/test/browser_tilt_02_notifications-seq.js
@@ -89,12 +89,13 @@ function cleanup() {
   info("Cleaning up the notifications test.");
 
   Services.obs.removeObserver(finalize, DESTROYED);
   Services.obs.removeObserver(obs_INITIALIZING, INITIALIZING);
   Services.obs.removeObserver(obs_INITIALIZED, INITIALIZED);
   Services.obs.removeObserver(obs_DESTROYING, DESTROYING);
   Services.obs.removeObserver(obs_BEFORE_DESTROYED, BEFORE_DESTROYED);
   Services.obs.removeObserver(obs_DESTROYED, DESTROYED);
+  Services.obs.removeObserver(obs_STARTUP, STARTUP);
 
   gBrowser.removeCurrentTab();
   finish();
 }

--- a/browser/devtools/tilt/test/browser_tilt_02_notifications.js
+++ b/browser/devtools/tilt/test/browser_tilt_02_notifications.js
@@ -113,16 +113,17 @@ function cleanup() {
   tab0 = null;
   tab1 = null;
 
   Services.obs.removeObserver(finalize, DESTROYED);
   Services.obs.removeObserver(tab_INITIALIZING, INITIALIZING);
   Services.obs.removeObserver(tab_DESTROYING, DESTROYING);
   Services.obs.removeObserver(tab_SHOWN, SHOWN);
   Services.obs.removeObserver(tab_HIDDEN, HIDDEN);
+  Services.obs.removeObserver(tab_STARTUP, STARTUP);
 
   gBrowser.tabContainer.removeEventListener("TabSelect", tabSelect);
   gBrowser.removeCurrentTab();
   finish();
 }
 
 function tabSelect() {
   if (testStep !== -1) {