diff --git a/content/buffer.js b/content/buffer.js
index 4d3dc88f..8b20f1dd 100644
--- a/content/buffer.js
+++ b/content/buffer.js
@@ -105,7 +105,7 @@ liberator.Buffer = function () //{{{
     function findScrollableWindow()
     {
         var win = window.document.commandDispatcher.focusedWindow;
-        if (win.scrollMaxX > 0 || win.scrollMaxY > 0)
+        if (win && (win.scrollMaxX > 0 || win.scrollMaxY > 0))
             return win;
 
         win = window.content;
diff --git a/content/ui.js b/content/ui.js
index aadaa566..9e560f66 100644
--- a/content/ui.js
+++ b/content/ui.js
@@ -1454,6 +1454,8 @@ liberator.StatusLine = function () //{{{
             if (!percent || typeof percent != "number")
             {
                 var win = document.commandDispatcher.focusedWindow;
+                if (!win)
+                    return;
                 percent = win.scrollMaxY == 0 ? -1 : win.scrollY / win.scrollMaxY;
             }