diff --git a/src/js/background.js b/src/js/background.js
index fa23ecee01..338e9d9299 100644
--- a/src/js/background.js
+++ b/src/js/background.js
@@ -34,10 +34,19 @@ var incognito = require("incognito");
 
 /**
  * Privacy Badger initializer.
+ *
+ * @param {Boolean} from_qunit don't intercept requests when run by unit tests
  */
-function Badger() {
+function Badger(from_qunit) {
   let self = this;
 
+  // important: must be executed synchronously
+  // to register a "persistent" onBeforeRequest listener in Firefox
+  // https://github.com/mdn/sprints/issues/1015
+  if (!from_qunit) {
+    webrequest.startBeforeReadyListener();
+  }
+
   self.webRTCAvailable = checkWebRTCBrowserSupport();
   self.firstPartyDomainPotentiallyRequired = testCookiesFirstPartyDomain();
 
@@ -81,6 +90,11 @@ function Badger() {
     await dntHashesPromise;
     await tabDataPromise;
 
+    if (from_qunit) {
+      self.INITIALIZED = true;
+      return;
+    }
+
     // start the listeners
     incognito.startListeners();
     webrequest.startListeners();
@@ -88,6 +102,8 @@ function Badger() {
     FirefoxAndroid.startListeners();
     startBackgroundListeners();
 
+    webrequest.stopBeforeReadyListener();
+
     console.log("Privacy Badger is ready to rock!");
     console.log("Set DEBUG=1 to view console messages.");
     self.INITIALIZED = true;
@@ -987,4 +1003,4 @@ function startBackgroundListeners() {
   });
 }
 
-var badger = window.badger = new Badger();
+let badger = window.badger = new Badger(document.location.pathname == "/tests/index.html");
diff --git a/src/js/webrequest.js b/src/js/webrequest.js
index 9b7b167886..fb4fbed7d4 100644
--- a/src/js/webrequest.js
+++ b/src/js/webrequest.js
@@ -34,7 +34,8 @@ var incognito = require("incognito");
 var utils = require("utils");
 
 /************ Local Variables *****************/
-var temporaryWidgetUnblock = {};
+let temporaryWidgetUnblock = {};
+let pendingTabs = new Set();
 
 /***************** Blocking Listener Functions **************/
 
@@ -50,6 +51,10 @@ function onBeforeRequest(details) {
     type = details.type,
     url = details.url;
 
+  if (utils.isRestrictedUrl(url)) {
+    return {};
+  }
+
   if (type == "main_frame") {
     forgetTab(tab_id);
     badger.recordFrame(tab_id, frame_id, url);
@@ -67,7 +72,7 @@ function onBeforeRequest(details) {
     return {cancel: true};
   }
 
-  if (_isTabChromeInternal(tab_id)) {
+  if (tab_id < 0) {
     return {};
   }
 
@@ -141,8 +146,8 @@ function onBeforeSendHeaders(details) {
     type = details.type,
     url = details.url;
 
-  if (_isTabChromeInternal(tab_id)) {
-    // DNT policy requests: strip cookies
+  if (tab_id < 0 || utils.isRestrictedUrl(url)) {
+    // strip cookies from DNT policy requests
     if (type == "xmlhttprequest" && url.endsWith("/.well-known/dnt-policy.txt")) {
       // remove Cookie headers
       let newHeaders = [];
@@ -157,6 +162,7 @@ function onBeforeSendHeaders(details) {
       };
     }
 
+    // ignore otherwise
     return {};
   }
 
@@ -239,8 +245,8 @@ function onHeadersReceived(details) {
   var tab_id = details.tabId,
     url = details.url;
 
-  if (_isTabChromeInternal(tab_id)) {
-    // DNT policy responses: strip cookies, reject redirects
+  if (tab_id < 0 || utils.isRestrictedUrl(url)) {
+    // strip cookies, reject redirects from DNT policy responses
     if (details.type == "xmlhttprequest" && url.endsWith("/.well-known/dnt-policy.txt")) {
       // if it's a redirect, cancel it
       if (details.statusCode >= 300 && details.statusCode < 400) {
@@ -262,6 +268,7 @@ function onHeadersReceived(details) {
       };
     }
 
+    // ignore otherwise
     return {};
   }
 
@@ -512,26 +519,6 @@ function checkAction(tabId, requestHost, frameId) {
   return badger.storage.getBestAction(requestHost);
 }
 
-/**
- * Checks if the tab is chrome internal
- *
- * @param {Integer} tabId Id of the tab to test
- * @returns {boolean} Returns true if the tab is chrome internal
- * @private
- */
-function _isTabChromeInternal(tabId) {
-  if (tabId < 0) {
-    return true;
-  }
-
-  let frameData = badger.getFrameData(tabId);
-  if (!frameData || !frameData.url.startsWith("http")) {
-    return true;
-  }
-
-  return false;
-}
-
 /**
  * Checks if the tab is a chrome-extension tab
  *
@@ -680,11 +667,6 @@ function dispatcher(request, sender, sendResponse) {
       return sendResponse();
     }
 
-    // Ignore requests from internal Chrome tabs.
-    if (_isTabChromeInternal(sender.tab.id)) {
-      return sendResponse();
-    }
-
     let frame_host = window.extractHostFromURL(request.frameUrl),
       tab_host = window.extractHostFromURL(sender.tab.url);
 
@@ -1059,17 +1041,57 @@ function dispatcher(request, sender, sendResponse) {
   }
 }
 
+
+/**
+ * Cancels all requests, populates list of pending tabs to be reloaded later,
+ * when Privacy Badger is ready.
+ *
+ * @param {Object} details chrome.webRequest request details
+ * @returns {Object}
+ */
+function onBeforeReady(details) {
+  if (!pendingTabs || details.tabId < 0) {
+    return;
+  }
+
+  pendingTabs.add(details.tabId);
+
+  return {
+    cancel: true
+  };
+}
+
+/**
+ * Reloads all tabs that loaded before Privacy Badger was ready.
+ */
+function reloadPendingTabs() {
+  for (let tab_id of pendingTabs) {
+    chrome.tabs.reload(tab_id);
+  }
+  pendingTabs = null;
+}
+
+
 /*************** Event Listeners *********************/
+function startBeforeReadyListener() {
+  chrome.webRequest.onBeforeRequest.addListener(onBeforeReady, {urls: ["<all_urls>"]}, ["blocking"]);
+}
+
+function stopBeforeReadyListener() {
+  chrome.webRequest.onBeforeRequest.removeListener(onBeforeReady);
+  reloadPendingTabs();
+}
+
 function startListeners() {
   chrome.webNavigation.onBeforeNavigate.addListener(onNavigate);
 
-  chrome.webRequest.onBeforeRequest.addListener(onBeforeRequest, {urls: ["http://*/*", "https://*/*"]}, ["blocking"]);
+  chrome.webRequest.onBeforeRequest.addListener(onBeforeRequest, {urls: ["<all_urls>"]}, ["blocking"]);
 
   let extraInfoSpec = ['requestHeaders', 'blocking'];
   if (chrome.webRequest.OnBeforeSendHeadersOptions.hasOwnProperty('EXTRA_HEADERS')) {
     extraInfoSpec.push('extraHeaders');
   }
-  chrome.webRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, {urls: ["http://*/*", "https://*/*"]}, extraInfoSpec);
+  chrome.webRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, {urls: ["<all_urls>"]}, extraInfoSpec);
 
   extraInfoSpec = ['responseHeaders', 'blocking'];
   if (chrome.webRequest.OnHeadersReceivedOptions.hasOwnProperty('EXTRA_HEADERS')) {
@@ -1083,8 +1105,11 @@ function startListeners() {
 }
 
 /************************************** exports */
-var exports = {};
-exports.startListeners = startListeners;
+let exports = {
+  startBeforeReadyListener,
+  startListeners,
+  stopBeforeReadyListener,
+};
 return exports;
 /************************************** exports */
 })();
diff --git a/tests/selenium/pbtest.py b/tests/selenium/pbtest.py
index 88a45bcdda..14e4080ff2 100644
--- a/tests/selenium/pbtest.py
+++ b/tests/selenium/pbtest.py
@@ -320,8 +320,10 @@ def run(self, result=None):
                     # wait for Badger's storage, listeners, ...
                     self.load_url(self.options_url)
                     self.wait_for_script(
-                        "return chrome.extension.getBackgroundPage()."
-                        "badger.INITIALIZED"
+                        "return ("
+                        "  chrome.extension &&"
+                        "  chrome.extension.getBackgroundPage().badger.INITIALIZED"
+                        ");"
                     )
                     driver.close()
                     if driver.window_handles: