diff --git a/src/log.py b/src/log.py
index 00c3559d3..244ec7cdd 100644
--- a/src/log.py
+++ b/src/log.py
@@ -65,6 +65,8 @@ class Formatter(logging.Formatter):
 
     def format(self, record):
         self._fmt = self._fmtConf()
+        if hasattr(self, '_style'): # Python 3
+            self._style._fmt = self._fmtConf()
         return logging.Formatter.format(self, record)