diff --git a/src/calibre/constants.py b/src/calibre/constants.py
index a2939ff96f..0444550597 100644
--- a/src/calibre/constants.py
+++ b/src/calibre/constants.py
@@ -2,7 +2,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
 __docformat__ = 'restructuredtext en'
 __appname__   = 'calibre'
-__version__   = '0.4.84b4'
+__version__   = '0.4.84b5'
 __author__    = "Kovid Goyal <kovid@kovidgoyal.net>"
 '''
 Various run time constants.
diff --git a/src/calibre/library/database.py b/src/calibre/library/database.py
index cf6b59d25e..947cd0697a 100644
--- a/src/calibre/library/database.py
+++ b/src/calibre/library/database.py
@@ -1418,6 +1418,8 @@ ALTER TABLE books ADD COLUMN isbn TEXT DEFAULT "" COLLATE NOCASE;
                     fmts = ''
                 for fmt in fmts.split(','):
                     data = self.format(idx, fmt, index_is_id=index_is_id)
+                    if not data:
+                        continue
                     fname = name +'.'+fmt.lower()
                     fname = sanitize_file_name(fname)
                     f = open(os.path.join(base, fname), 'w+b')
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 4c7ee725d8..1e3b577ead 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -281,6 +281,8 @@ class LibraryDatabase2(LibraryDatabase):
             for format in formats:
                 # Get data as string (cant use file as source and target files may be the same)
                 f = self.format(id, format, index_is_id=True, as_file=False)
+                if not  f:
+                    continue
                 stream = cStringIO.StringIO(f)
                 self.add_format(id, format, stream, index_is_id=True, path=tpath)
         self.conn.execute('UPDATE books SET path=? WHERE id=?', (path, id))
@@ -344,6 +346,7 @@ class LibraryDatabase2(LibraryDatabase):
             if os.access(path, os.R_OK|os.W_OK):
                 f = open(path, mode)
                 return f if as_file else f.read()
+            self.remove_format(id, format, index_is_id=True)
         
     def add_format(self, index, format, stream, index_is_id=False, path=None):
         id = index if index_is_id else self.id(index)
@@ -384,7 +387,7 @@ class LibraryDatabase2(LibraryDatabase):
             ext = ('.' + format.lower()) if format else ''
             path = os.path.join(path, name+ext)
             if os.access(path, os.W_OK):
-                os.unlink(path)
+                os.remove(path)
             self.conn.execute('DELETE FROM data WHERE book=? AND format=?', (id, format.upper()))
             self.conn.commit()