diff -r d08e3586dde3 Lib/logging/config.py
--- a/Lib/logging/config.py	Thu Apr 10 07:07:59 2014 +0100
+++ b/Lib/logging/config.py	Fri Apr 11 23:33:24 2014 +0200
@@ -670,7 +670,12 @@
         else:
             fmt = config.get('format', None)
             dfmt = config.get('datefmt', None)
-            result = logging.Formatter(fmt, dfmt)
+            cname = config.get('class', None)
+            if cname:
+                c = _resolve(cname)
+                result = c(fmt, dfmt)
+            else:
+                result = logging.Formatter(fmt, dfmt)
         return result
 
     def configure_filter(self, config):