From 97386ccb9d5ce41a20e517ad65e8de1aa8f07384 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 10 Jun 2009 23:04:40 -0700
Subject: [PATCH] Fix #2572 (Error when Restoring from Tray)

---
 src/calibre/ebooks/metadata/__init__.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/calibre/ebooks/metadata/__init__.py b/src/calibre/ebooks/metadata/__init__.py
index 1a5af8966c..4c2c6c744a 100644
--- a/src/calibre/ebooks/metadata/__init__.py
+++ b/src/calibre/ebooks/metadata/__init__.py
@@ -61,8 +61,9 @@ def roman(num):
 
 
 def fmt_sidx(i, fmt='%.2f', use_roman=False):
-    if i is None:
+    if i is None or i == '':
         i = 1
+    i = float(i)
     if int(i) == float(i):
         return roman(int(i)) if use_roman else '%d'%int(i)
     try: