diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 561640668ff8..bb56a7174ba1 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -6976,6 +6976,7 @@ let gPrivateBrowsingUI = {
       docElement.setAttribute("titlemodifier",
         docElement.getAttribute("titlemodifier_privatebrowsing"));
       docElement.setAttribute("browsingmode", "private");
+      gBrowser.updateTitlebar();
     }
 
     setTimeout(function () {
diff --git a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_windowtitle.js b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_windowtitle.js
index 10bf8b9b33be..f0335efb876d 100644
--- a/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_windowtitle.js
+++ b/browser/components/privatebrowsing/test/browser/browser_privatebrowsing_windowtitle.js
@@ -54,87 +54,83 @@ function test() {
   let test_title = "Test title";
   let app_name = document.documentElement.getAttribute("title");
   const isOSX = ("nsILocalFileMac" in Ci);
-    var page_with_title;
-    var page_without_title;
-    var pb_page_with_title;
-    var pb_page_without_title;
-    var about_pb_title;
+  let page_with_title;
+  let page_without_title;
+  let about_pb_title;
+  let pb_page_with_title;
+  let pb_page_without_title;
+  let pb_about_pb_title;
   if (isOSX) {
     page_with_title = test_title;
     page_without_title = app_name;
+    about_pb_title = "Would you like to start Private Browsing?";
     pb_page_with_title = test_title + " - (Private Browsing)";
     pb_page_without_title = app_name + " - (Private Browsing)";
-    about_pb_title = pb_page_without_title;
+    pb_about_pb_title = pb_page_without_title;
   }
   else {
     page_with_title = test_title + " - " + app_name;
     page_without_title = app_name;
+    about_pb_title = "Would you like to start Private Browsing?" + " - " + app_name;
     pb_page_with_title = test_title + " - " + app_name + " (Private Browsing)";
     pb_page_without_title = app_name + " (Private Browsing)";
-    about_pb_title = "Private Browsing - " + app_name + " (Private Browsing)";
+    pb_about_pb_title = "Private Browsing - " + app_name + " (Private Browsing)";
   }
 
-  // check the window title for a page without a title
-  let blankTab = gBrowser.addTab();
-  gBrowser.selectedTab = blankTab;
-  is(document.title, page_without_title, "The window title for a page without a title matches " +
-    "(outside private browsing mode)");
-  gBrowser.removeTab(blankTab);
+  function testTabTitle(url, insidePB, expected_title, funcNext) {
+    pb.privateBrowsingEnabled = insidePB;
 
-  let pageTab = gBrowser.addTab();
-  gBrowser.selectedTab = pageTab;
-  let pageBrowser = gBrowser.getBrowserForTab(pageTab);
-  pageBrowser.addEventListener("load", function () {
-    pageBrowser.removeEventListener("load", arguments.callee, true);
+    let tab = gBrowser.addTab();
+    gBrowser.selectedTab = tab;
+    let browser = gBrowser.getBrowserForTab(tab);
+    browser.addEventListener("load", function() {
+      browser.removeEventListener("load", arguments.callee, true);
 
-    // check the window title for a page with a title
-    is(document.title, page_with_title, "The window title for a page with a title matches " +
-      "(outside private browsing mode)");
+      // ensure that the test is run after the page onload event
+      setTimeout(function() {
+        setTimeout(function() {
+          is(document.title, expected_title, "The window title for " + url +
+             " is correct (" + (insidePB ? "inside" : "outside") +
+             " private browsing mode)");
 
-    gBrowser.removeTab(pageTab);
+          let win = gBrowser.replaceTabWithWindow(tab);
+          win.addEventListener("load", function() {
+            win.removeEventListener("load", arguments.callee, false);
 
-    // enter the private browsing mode
-    pb.privateBrowsingEnabled = true;
+            // ensure that the test is run after delayedStartup
+            setTimeout(function() {
+              setTimeout(function() {
+                is(win.document.title, expected_title, "The window title for " + url +
+                   " detahced tab is correct (" + (insidePB ? "inside" : "outside") +
+                   " private browsing mode)");
+                win.close();
 
-    // check the window title for a page without a title
-    blankTab = gBrowser.addTab();
-    gBrowser.selectedTab = blankTab;
-    is(document.title, pb_page_without_title, "The window title for a page without a title matches " +
-      "(inside private browsing mode)");
-    gBrowser.removeTab(blankTab);
-
-    pageTab = gBrowser.addTab();
-    gBrowser.selectedTab = pageTab;
-    pageBrowser = gBrowser.getBrowserForTab(pageTab);
-    pageBrowser.addEventListener("load", function () {
-      pageBrowser.removeEventListener("load", arguments.callee, true);
-
-      // check the window title for a page with a title
-      is(document.title, pb_page_with_title, "The window title for a page with a title matches " +
-        "(inside private browsing mode)");
-
-      gBrowser.removeTab(pageTab);
-
-      let aboutPBTab = gBrowser.addTab();
-      gBrowser.selectedTab = aboutPBTab;
-      let aboutPBBrowser = gBrowser.getBrowserForTab(aboutPBTab);
-      aboutPBBrowser.addEventListener("load", function() {
-        aboutPBBrowser.removeEventListener("load", arguments.callee, true);
-
-        // check the window title for about:privatebrowsing
-        is(document.title, about_pb_title, "The window title for about:privatebrowsing matches " +
-          "(inside private browsing mode)");
-
-        gBrowser.removeTab(aboutPBTab);
-
-        // cleanup
-        pb.privateBrowsingEnabled = false;
-        prefBranch.clearUserPref("browser.privatebrowsing.keep_current_session");
-        finish();
-      }, true);
-      aboutPBBrowser.contentWindow.location = "about:privatebrowsing";
+                funcNext();
+              }, 0);
+            }, 0);
+          }, false);
+        }, 0);
+      }, 0);
     }, true);
-    pageBrowser.contentWindow.location = testPageURL;
-  }, true);
-  pageBrowser.contentWindow.location = testPageURL;
+    browser.loadURI(url);
+  }
+
+  function cleanup() {
+    pb.privateBrowsingEnabled = false;
+    prefBranch.clearUserPref("browser.privatebrowsing.keep_current_session");
+    finish();
+  }
+
+  testTabTitle("about:blank", false, page_without_title, function() {
+    testTabTitle(testPageURL, false, page_with_title, function() {
+      testTabTitle("about:privatebrowsing", false, about_pb_title, function() {
+        testTabTitle("about:blank", true, pb_page_without_title, function() {
+          testTabTitle(testPageURL, true, pb_page_with_title, function() {
+            testTabTitle("about:privatebrowsing", true, pb_about_pb_title, cleanup);
+          });
+        });
+      });
+    });
+  });
+  return;
 }