diff --git a/cps/db.py b/cps/db.py
index 48d2247d..66795f7e 100644
--- a/cps/db.py
+++ b/cps/db.py
@@ -51,8 +51,6 @@ try:
 except ImportError:
     use_unidecode = False
 
-Session = None
-
 cc_exceptions = ['datetime', 'comments', 'composite', 'series']
 cc_classes = {}
 
@@ -439,9 +437,6 @@ class CalibreDB():
         cls.config = config
         cls.dispose()
 
-        # todo: remove...?
-        global Session
-
         if not config.config_calibre_dir:
             config.invalidate()
             return False
diff --git a/cps/tasks/convert.py b/cps/tasks/convert.py
index 2b679fc0..8179de9f 100644
--- a/cps/tasks/convert.py
+++ b/cps/tasks/convert.py
@@ -53,7 +53,7 @@ class TaskConvert(CalibreTask):
 
     def _convert_ebook_format(self):
         error_message = None
-        local_session = db.Session()
+        local_session = db.CalibreDB()
         file_path = self.file_path
         book_id = self.bookid
         format_old_ext = u'.' + self.settings['old_book_format'].lower()