diff --git a/activesupport/lib/active_support/core_ext/logger.rb b/activesupport/lib/active_support/core_ext/logger.rb
index c4994ca2ee00c05e1eafeda303729242ebdda269..d023b4bcff1ab2d1ee4291b6c617f57bd7cd8e94 100644
--- a/activesupport/lib/active_support/core_ext/logger.rb
+++ b/activesupport/lib/active_support/core_ext/logger.rb
@@ -72,44 +72,6 @@ def formatter
     @formatter ||= SimpleFormatter.new
   end
 
-  unless const_defined? :Formatter
-    class Formatter
-      Format = "%s, [%s#%d] %5s -- %s: %s\n"
-
-      attr_accessor :datetime_format
-
-      def initialize
-        @datetime_format = nil
-      end
-
-      def call(severity, time, progname, msg)
-        Format % [severity[0..0], format_datetime(time), $$, severity, progname,
-        msg2str(msg)]
-      end
-
-      private
-        def format_datetime(time)
-          if @datetime_format.nil?
-            time.strftime("%Y-%m-%dT%H:%M:%S.") << "%06d " % time.usec
-          else
-            time.strftime(@datetime_format)
-          end
-        end
-
-        def msg2str(msg)
-          case msg
-          when ::String
-            msg
-          when ::Exception
-            "#{ msg.message } (#{ msg.class })\n" <<
-            (msg.backtrace || []).join("\n")
-          else
-            msg.inspect
-          end
-        end
-    end
-  end
-
   # Simple formatter which only displays the message.
   class SimpleFormatter < Logger::Formatter
     # This method is invoked when a log event occurs