--- a/viewer.py	Wed Jun 15 15:55:13 2016 +0800
+++ b/viewer.py	Wed Jun 15 20:50:33 2016 +0800
@@ -88,7 +88,8 @@
         database.init(rel('database.sqlite'))
 
     def listen(self, port, address='', **kwargs):
-        logging.info('{} is serving on {}:{}'.format(self.__class__.__name__, address, port))
+        name = self.__class__.__name__
+        logging.info('%s is serving on %s:%d', name, address, port)
         super(CandolintViewer, self).listen(port, address, **kwargs)