--- a/browser/modules/RecentWindow.jsm
+++ b/browser/modules/RecentWindow.jsm
@@ -28,16 +28,17 @@ this.RecentWindow = {
   getMostRecentBrowserWindow: function RW_getMostRecentBrowserWindow(aOptions) {
     let checkPrivacy = typeof aOptions == "object" &&
                        "private" in aOptions;
 
     function isSuitableBrowserWindow(win) {
       return (!win.closed &&
               win.toolbar.visible &&
               (!checkPrivacy ||
+               PrivateBrowsingUtils.permanentPrivateBrowsing ||
                PrivateBrowsingUtils.isWindowPrivate(win) == aOptions.private));
     }
 
 #ifdef BROKEN_WM_Z_ORDER
     let win = Services.wm.getMostRecentWindow("navigator:browser");
 
     // if we're lucky, this isn't a popup, and we can just return this
     if (win && !isSuitableBrowserWindow(win)) {