From 36b1a697c2ed5bc3aa594bd28172f40a32861242 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 6 Nov 2014 09:29:19 +0530
Subject: [PATCH] ...

---
 src/calibre/gui2/tweak_book/preview.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/calibre/gui2/tweak_book/preview.py b/src/calibre/gui2/tweak_book/preview.py
index cc9eae3b9d..8083ec051d 100644
--- a/src/calibre/gui2/tweak_book/preview.py
+++ b/src/calibre/gui2/tweak_book/preview.py
@@ -129,7 +129,7 @@ class ParseWorker(Thread):
         self.parse_items.clear()
 
     def is_alive(self):
-        return Thread.is_alive(self) or self.worker.is_alive()
+        return Thread.is_alive(self) or (hasattr(self, 'worker') and self.worker.is_alive())
 
 parse_worker = ParseWorker()
 # }}}