diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 83c776ea4..1ff5fad85 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -78,8 +78,10 @@ window.addEventListener('unload', function() {
         vAPI.app.onShutdown();
     }
 
-    for ( var cleanup of cleanupTasks ) {
-        cleanup();
+    // IMPORTANT: cleanup tasks must be executed using LIFO order.
+    var i = cleanupTasks.length;
+    while ( i-- ) {
+        cleanupTasks[i]();
     }
 
     if ( cleanupTasks.length < expectedNumberOfCleanups ) {
@@ -2865,17 +2867,18 @@ vAPI.toolbarButton = {
     };
 
     var shutdown = function() {
-        CustomizableUI.removeListener(CUIEvents);
-        CustomizableUI.destroyWidget(tbb.id);
-
         for ( var win of winWatcher.getWindows() ) {
             var panel = win.document.getElementById(tbb.viewId);
-            panel.parentNode.removeChild(panel);
+            if ( panel !== null && panel.parentNode !== null ) {
+                panel.parentNode.removeChild(panel);
+            }
             win.QueryInterface(Ci.nsIInterfaceRequestor)
                 .getInterface(Ci.nsIDOMWindowUtils)
                 .removeSheet(styleURI, 1);
         }
 
+        CustomizableUI.removeListener(CUIEvents);
+        CustomizableUI.destroyWidget(tbb.id);
 
         vAPI.messaging.globalMessageManager.removeMessageListener(
             location.host + ':closePopup',
diff --git a/src/js/popup.js b/src/js/popup.js
index cddc69cb0..cbba06b0d 100644
--- a/src/js/popup.js
+++ b/src/js/popup.js
@@ -126,10 +126,12 @@ var cachePopupData = function(data) {
             continue;
         }
         domain = hostnameDict[hostname].domain;
+        prefix = hostname.slice(0, 0 - domain.length);
+        // Prefix with space char for 1st-party hostnames: this ensure these
+        // will come first in list.
         if ( domain === popupData.pageDomain ) {
             domain = '\u0020';
         }
-        prefix = hostname.slice(0, 0 - domain.length);
         hostnameToSortableTokenMap[hostname] = domain + prefix.split('.').reverse().join('.');
     }
     return popupData;