From 73583f616bfb30a2a09a1153c04d6060fb690cf2 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 4 Jul 2012 10:37:08 +0530
Subject: [PATCH] ...

---
 src/calibre/gui2/book_details.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/calibre/gui2/book_details.py b/src/calibre/gui2/book_details.py
index 6bc8d878ad..3e57442591 100644
--- a/src/calibre/gui2/book_details.py
+++ b/src/calibre/gui2/book_details.py
@@ -104,9 +104,10 @@ def render_data(mi, use_roman_numbers=True, all_fields=False):
             field = 'title_sort'
         if all_fields:
             display = True
-        isnull = mi.is_null(field)
         if metadata['datatype'] == 'bool':
             isnull = mi.get(field) is None
+        else:
+            isnull = mi.is_null(field)
         if (not display or not metadata or isnull or field == 'comments'):
             continue
         name = metadata['name']