diff --git a/addons/mail/mail_thread.py b/addons/mail/mail_thread.py
index 112dff6bac6..79bf92cb68d 100644
--- a/addons/mail/mail_thread.py
+++ b/addons/mail/mail_thread.py
@@ -385,7 +385,7 @@ class mail_thread(osv.AbstractModel):
         if not context.get('mail_notrack'):
             tracked_fields = self._get_tracked_fields(cr, uid, values.keys(), context=track_ctx)
             if tracked_fields:
-                initial_values = {thread_id: dict((item, False) for item in tracked_fields)}
+                initial_values = {thread_id: dict.fromkeys(tracked_fields, False)}
                 self.message_track(cr, uid, [thread_id], tracked_fields, initial_values, context=track_ctx)
         return thread_id
 
@@ -398,25 +398,24 @@ class mail_thread(osv.AbstractModel):
         track_ctx = dict(context)
         if 'lang' not in track_ctx:
             track_ctx['lang'] = self.pool.get('res.users').browse(cr, uid, uid, context=context).lang
+
+        tracked_fields = None
         if not context.get('mail_notrack'):
             tracked_fields = self._get_tracked_fields(cr, uid, values.keys(), context=track_ctx)
-        else:
-            tracked_fields = []
+
         if tracked_fields:
             records = self.browse(cr, uid, ids, context=track_ctx)
-            initial_values = dict((this.id, dict((key, getattr(this, key)) for key in tracked_fields.keys())) for this in records)
+            initial_values = dict((record.id, dict((key, getattr(record, key)) for key in tracked_fields))
+                                  for record in records)
 
         # Perform write, update followers
         result = super(mail_thread, self).write(cr, uid, ids, values, context=context)
         self.message_auto_subscribe(cr, uid, ids, values.keys(), context=context, values=values)
 
-        if not context.get('mail_notrack'):
-            # Perform the tracking
-            tracked_fields = self._get_tracked_fields(cr, uid, values.keys(), context=context)
-        else:
-            tracked_fields = None
+        # Perform the tracking
         if tracked_fields:
             self.message_track(cr, uid, ids, tracked_fields, initial_values, context=track_ctx)
+
         return result
 
     def unlink(self, cr, uid, ids, context=None):
@@ -453,14 +452,15 @@ class mail_thread(osv.AbstractModel):
             :return list: a list of (field_name, column_info obj), containing
                 always tracked fields and modified on_change fields
         """
-        lst = []
+        tracked_fields = []
         for name, column_info in self._all_columns.items():
             visibility = getattr(column_info.column, 'track_visibility', False)
             if visibility == 'always' or (visibility == 'onchange' and name in updated_fields) or name in self._track:
-                lst.append(name)
-        if not lst:
-            return lst
-        return self.fields_get(cr, uid, lst, context=context)
+                tracked_fields.append(name)
+
+        if tracked_fields:
+            return self.fields_get(cr, uid, tracked_fields, context=context)
+        return {}
 
     def message_track(self, cr, uid, ids, tracked_fields, initial_values, context=None):
 
@@ -1871,4 +1871,4 @@ class mail_thread(osv.AbstractModel):
         message_obj.write(cr, uid, msg_ids_comment, {"res_id" : new_res_id, "model" : new_model}, context=context)
         message_obj.write(cr, uid, msg_ids_not_comment, {"res_id" : new_res_id, "model" : new_model, "subtype_id" : None}, context=context)
         
-        return True
\ No newline at end of file
+        return True