--- a/browser/components/preferences/in-content/privacy.js
+++ b/browser/components/preferences/in-content/privacy.js
@@ -242,17 +242,17 @@ var gPrivacyPane = {
   {
     let mode = document.getElementById("historyMode");
     let autoStart = document.getElementById("privateBrowsingAutoStart");
     this._lastMode = mode.selectedIndex;
     this._lastCheckState = autoStart.hasAttribute('checked');
   },
 
   _lastMode: null,
-  _lasCheckState: null,
+  _lastCheckState: null,
   updateAutostart: function PPP_updateAutostart() {
       let mode = document.getElementById("historyMode");
       let autoStart = document.getElementById("privateBrowsingAutoStart");
       let pref = document.getElementById("browser.privatebrowsing.autostart");
       if ((mode.value == "custom" && this._lastCheckState == autoStart.checked) ||
           (mode.value == "remember" && !this._lastCheckState) ||
           (mode.value == "dontremember" && this._lastCheckState)) {
           // These are all no-op changes, so we don't need to prompt.
@@ -294,16 +294,17 @@ var gPrivacyPane = {
 
       this._shouldPromptForRestart = false;
 
       if (this._lastCheckState) {
         autoStart.checked = "checked";
       } else {
         autoStart.removeAttribute('checked');
       }
+      pref.value = autoStart.hasAttribute('checked');
       mode.selectedIndex = this._lastMode;
       mode.doCommand();
 
       this._shouldPromptForRestart = true;
   },
 
   // HISTORY
 

--- a/browser/components/preferences/privacy.js
+++ b/browser/components/preferences/privacy.js
@@ -244,17 +244,17 @@ var gPrivacyPane = {
   {
     let mode = document.getElementById("historyMode");
     let autoStart = document.getElementById("privateBrowsingAutoStart");
     this._lastMode = mode.selectedIndex;
     this._lastCheckState = autoStart.hasAttribute('checked');
   },
 
   _lastMode: null,
-  _lasCheckState: null,
+  _lastCheckState: null,
   updateAutostart: function PPP_updateAutostart() {
       let mode = document.getElementById("historyMode");
       let autoStart = document.getElementById("privateBrowsingAutoStart");
       let pref = document.getElementById("browser.privatebrowsing.autostart");
       if ((mode.value == "custom" && this._lastCheckState == autoStart.checked) ||
           (mode.value == "remember" && !this._lastCheckState) ||
           (mode.value == "dontremember" && this._lastCheckState)) {
           // These are all no-op changes, so we don't need to prompt.
@@ -296,16 +296,17 @@ var gPrivacyPane = {
 
       this._shouldPromptForRestart = false;
 
       if (this._lastCheckState) {
         autoStart.checked = "checked";
       } else {
         autoStart.removeAttribute('checked');
       }
+      pref.value = autoStart.hasAttribute('checked');
       mode.selectedIndex = this._lastMode;
       mode.doCommand();
 
       this._shouldPromptForRestart = true;
   },
 
   // HISTORY