diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 72c187fc6..b22a23910 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
-    µBlock - a browser extension to block requests.
-    Copyright (C) 2014 The µBlock authors
+    uBlock Origin - a browser extension to block requests.
+    Copyright (C) 2014-2106 The uBlock Origin authors
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -62,7 +62,7 @@ var deferUntil = function(testFn, mainFn, details) {
         vAPI.setTimeout(check, next);
     };
 
-    if ( details.async === false ) {
+    if ( 'sync' in details && details.sync === true ) {
         check();
     } else {
         vAPI.setTimeout(check, 1);
@@ -829,7 +829,7 @@ vAPI.tabs.get = function(tabId, callback) {
         id: tabId,
         index: tabWatcher.indexFromTarget(browser),
         windowId: winWatcher.idFromWindow(win),
-        active: browser === tabBrowser.selectedBrowser,
+        active: tabBrowser !== null && browser === tabBrowser.selectedBrowser,
         url: browser.currentURI.asciiSpec,
         title: browser.contentTitle
     });
@@ -921,6 +921,9 @@ vAPI.tabs.open = function(details) {
 
     var win = winWatcher.getCurrentWindow();
     var tabBrowser = getTabBrowser(win);
+    if ( tabBrowser === null ) {
+        return;
+    }
 
     if ( vAPI.fennec ) {
         tabBrowser.addTab(details.url, {
@@ -1430,7 +1433,7 @@ vAPI.setIcon = function(tabId, iconStatus, badge) {
         : winWatcher.getCurrentWindow();
     var curTabId;
     var tabBrowser = getTabBrowser(win);
-    if ( tabBrowser ) {
+    if ( tabBrowser !== null ) {
         curTabId = tabWatcher.tabIdFromTarget(tabBrowser.selectedTab);
     }
     var tb = vAPI.toolbarButton;
@@ -2038,12 +2041,12 @@ var httpObserver = {
             return false;
         }
 
-        if ( result.cancel === true ) {
+        if ( 'cancel' in result && result.cancel === true ) {
             channel.cancel(this.ABORT);
             return true;
         }
 
-        if ( result.redirectUrl ) {
+        if ( 'redirectUrl' in result ) {
             channel.redirectionLimit = 1;
             channel.redirectTo(Services.io.newURI(result.redirectUrl, null, null));
             return true;
diff --git a/platform/firefox/vapi-client.js b/platform/firefox/vapi-client.js
index ce9e3d228..e19dade01 100644
--- a/platform/firefox/vapi-client.js
+++ b/platform/firefox/vapi-client.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
-    µBlock - a browser extension to block requests.
-    Copyright (C) 2014 The µBlock authors
+    uBlock Origin - a browser extension to block requests.
+    Copyright (C) 2014-2016 The uBlock Origin authors
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -131,12 +131,15 @@ vAPI.messaging = {
                 return;
             }
             var details = msg.details;
-            if ( details.allFrames !== true && window !== window.top ) {
+            // Whether to inject in all child frames. Default to only top frame.
+            var allFrames = details.allFrames || false;
+            if ( allFrames !== true && window !== window.top ) {
                 return;
             }
             // https://github.com/gorhill/uBlock/issues/876
             // Enforce `details.runAt`. Default to `document_end`.
-            if ( details.runAt === 'document_start' || document.readyState !== 'loading' ) {
+            var runAt = details.runAt || 'document_end';
+            if ( runAt === 'document_start' || document.readyState !== 'loading' ) {
                 self.injectScript(details.file);
                 return;
             }
diff --git a/src/js/messaging.js b/src/js/messaging.js
index b337b9160..a972f2ee1 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
-    uBlock - a browser extension to block requests.
-    Copyright (C) 2014-2015 Raymond Hill
+    uBlock Origin - a browser extension to block requests.
+    Copyright (C) 2014-2016 Raymond Hill
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -131,7 +131,7 @@ var onMessage = function(request, sender, callback) {
     case 'launchElementPicker':
         // Launched from some auxiliary pages, clear context menu coords.
         µb.mouseX = µb.mouseY = -1;
-        µb.elementPickerExec(request.tabId, request.targetURL);
+        µb.elementPickerExec(request.tabId, request.targetURL || '');
         break;
 
     case 'gotoURL':
diff --git a/src/js/pagestore.js b/src/js/pagestore.js
index ff534d5fb..fb06bd58c 100644
--- a/src/js/pagestore.js
+++ b/src/js/pagestore.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
-    uBlock - a browser extension to block requests.
-    Copyright (C) 2014-2015 Raymond Hill
+    uBlock Origin - a browser extension to block requests.
+    Copyright (C) 2014-2016 Raymond Hill
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -19,8 +19,6 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* global µBlock */
-
 /*******************************************************************************
 
 A PageRequestStore object is used to store net requests in two ways:
@@ -229,25 +227,23 @@ var frameStoreJunkyardMax = 50;
 
 /******************************************************************************/
 
-var FrameStore = function(rootHostname, frameURL) {
-    this.init(rootHostname, frameURL);
+var FrameStore = function(frameURL) {
+    this.init(frameURL);
 };
 
 /******************************************************************************/
 
-FrameStore.factory = function(rootHostname, frameURL) {
+FrameStore.factory = function(frameURL) {
     var entry = frameStoreJunkyard.pop();
     if ( entry === undefined ) {
-        entry = new FrameStore(rootHostname, frameURL);
-    } else {
-        entry.init(rootHostname, frameURL);
+        return new FrameStore(frameURL);
     }
-    return entry;
+    return entry.init(frameURL);
 };
 
 /******************************************************************************/
 
-FrameStore.prototype.init = function(rootHostname, frameURL) {
+FrameStore.prototype.init = function(frameURL) {
     var µburi = µb.URI;
     this.pageHostname = µburi.hostnameFromURI(frameURL);
     this.pageDomain = µburi.domainFromHostname(this.pageHostname) || this.pageHostname;
@@ -423,9 +419,9 @@ PageStore.prototype.getFrame = function(frameId) {
 PageStore.prototype.setFrame = function(frameId, frameURL) {
     var frameStore = this.frames[frameId];
     if ( frameStore ) {
-        frameStore.init(this.rootHostname, frameURL);
+        frameStore.init(frameURL);
     } else {
-        this.frames[frameId] = FrameStore.factory(this.rootHostname, frameURL);
+        this.frames[frameId] = FrameStore.factory(frameURL);
     }
 };