diff --git a/README.md b/README.md
index 4ff7441..02f5372 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,8 @@ Or install it yourself as:
 RailsBigBrother.config do |config|
   config.format = "big_brother;%<user>s;%<controller_info>s;%<class>s;%<id>s;%<action>s;%<args>s"
   config.logger = Rails.logger
+  config.hash_to_s = proc { |hash| hash.map { |k,v| "#{k}:#{v}" }.join(',') }
+  config.array_to_s = proc { |array| array.join(',') }
 end
 ```
 
diff --git a/lib/rails_big_brother.rb b/lib/rails_big_brother.rb
index 9b72993..4a073d7 100644
--- a/lib/rails_big_brother.rb
+++ b/lib/rails_big_brother.rb
@@ -4,7 +4,19 @@ require "rails_big_brother/model"
 
 module RailsBigBrother
   class << self
-    attr_writer :format, :logger
+    attr_writer :array_to_s, :hash_to_s, :format, :logger
+
+    def array_to_s
+      @array_to_s ||= Proc.new do |array|
+        array.join(',')
+      end
+    end
+
+    def hash_to_s
+      @hash_to_s ||= Proc.new do |hash|
+        hash.map { |k,v| "#{k}:#{v}" }.join(',')
+      end
+    end
 
     def logger
       @logger ||= Rails.logger
@@ -37,9 +49,9 @@ module RailsBigBrother
     def controller_info_string
       case controller_info
       when Array
-        controller_info.join(',')
+        array_to_s.call(controller_info)
       when Hash
-        controller_info.map { |k,v| "#{k}:#{v}" }.join(',')
+        hash_to_s.call(controller_info)
       else
         controller_info
       end
diff --git a/lib/rails_big_brother/model.rb b/lib/rails_big_brother/model.rb
index 0892789..6b40f77 100644
--- a/lib/rails_big_brother/model.rb
+++ b/lib/rails_big_brother/model.rb
@@ -34,12 +34,15 @@ module RailsBigBrother
         changed_fields = changed_fields & self.class.big_brother_options[:only] if self.class.big_brother_options.has_key?(:only)
 
         unless changed_fields.empty?
-          changed_fields_string = changed_fields.map do |f|
-              f + (
+          fields_hash = changed_fields.inject({}) do |hash, field|
+            hash[field] = (
                 self.class.big_brother_options.has_key?(:verbose) &&
-                self.class.big_brother_options[:verbose].include?(f) ? ":#{send(f)}" : '')
-            end.join(',')
-          big_brother_log 'update', changed_fields_string
+                self.class.big_brother_options[:verbose].include?(field) ? send(field).to_s : ''
+            )
+
+            hash
+          end
+          big_brother_log 'update', RailsBigBrother.hash_to_s.call(fields_hash)
         end
       end
 
@@ -55,7 +58,7 @@ module RailsBigBrother
           class: self.class.name,
           id: self.to_param,
           action: action,
-          args: args.join(',')
+          args: RailsBigBrother.array_to_s.call(args)
         }
       end
     end