diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 966daec77..67fa567b1 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -998,10 +998,9 @@ var tabWatcher = (function() {
         }
 
         var tabContainer = null;
-        if ( tabBrowser.deck ) {
-            // Fennec
+        if ( tabBrowser.deck ) {                    // Fennec
             tabContainer = tabBrowser.deck;
-        } else if ( tabBrowser.tabContainer ) {
+        } else if ( tabBrowser.tabContainer ) {     // Firefox
             tabContainer = tabBrowser.tabContainer;
         }
         if ( tabContainer ) {
@@ -1025,6 +1024,7 @@ var tabWatcher = (function() {
             browser = browserFromTarget(tab);
             tabId = browserToTabIdMap.get(browser);
             if ( tabId !== undefined ) {
+                removeBrowserEntry(tabId, browser);
                 tabIdToBrowserMap.delete(tabId);
             }
             browserToTabIdMap.delete(browser);
@@ -1036,6 +1036,11 @@ var tabWatcher = (function() {
         observe: function(win, topic) {
             if ( topic === 'domwindowopened' ) {
                 win.addEventListener('DOMContentLoaded', onWindowLoad);
+                return;
+            }
+            if ( topic === 'domwindowclosed' ) {
+                onWindowUnload.call(win);
+                return;
             }
         }
     };