diff --git a/lib/validates_timeliness/active_record/multiparameter_attributes.rb b/lib/validates_timeliness/active_record/multiparameter_attributes.rb
index 735dd2a..463eaa8 100644
--- a/lib/validates_timeliness/active_record/multiparameter_attributes.rb
+++ b/lib/validates_timeliness/active_record/multiparameter_attributes.rb
@@ -5,6 +5,33 @@ module ValidatesTimeliness
   end
 
   module ActiveRecord
+
+    class << self
+
+      def time_array_to_string(values, type)
+        values.collect! {|v| v.to_s }
+
+        case type
+        when :date
+          extract_date_from_multiparameter_attributes(values)
+        when :time
+          extract_time_from_multiparameter_attributes(values)
+        when :datetime
+          extract_date_from_multiparameter_attributes(values) + " " + extract_time_from_multiparameter_attributes(values)
+        end
+      end
+
+      def extract_date_from_multiparameter_attributes(values)
+        year = ValidatesTimeliness::Formats.unambiguous_year(values[0].rjust(2, "0"))
+        [year, *values.slice(1, 2).map { |s| s.rjust(2, "0") }].join("-")
+      end
+
+      def extract_time_from_multiparameter_attributes(values)
+        values[3..5].map { |s| s.rjust(2, "0") }.join(":")
+      end
+
+    end
+
     module MultiparameterAttributes
       
       def self.included(base)
@@ -23,7 +50,7 @@ module ValidatesTimeliness
               if values.empty?
                 send("#{name}=", nil)
               else
-                value = time_array_to_string(values, column.type)
+                value = ValidatesTimeliness::ActiveRecord.time_array_to_string(values, column.type)
                 send("#{name}=", value)
               end
             rescue => ex
@@ -37,28 +64,6 @@ module ValidatesTimeliness
         execute_callstack_for_multiparameter_attributes_without_timeliness(callstack)
       end
       
-      def time_array_to_string(values, type)
-        values.collect! {|v| v.to_s }
-                
-        case type
-        when :date
-          extract_date_from_multiparameter_attributes(values)
-        when :time
-          extract_time_from_multiparameter_attributes(values)
-        when :datetime
-          extract_date_from_multiparameter_attributes(values) + " " + extract_time_from_multiparameter_attributes(values)
-        end
-      end   
-         
-      def extract_date_from_multiparameter_attributes(values)
-        year = ValidatesTimeliness::Formats.unambiguous_year(values[0].rjust(2, "0"))
-        [year, *values.slice(1, 2).map { |s| s.rjust(2, "0") }].join("-")
-      end
-      
-      def extract_time_from_multiparameter_attributes(values)
-        values[3..5].map { |s| s.rjust(2, "0") }.join(":")
-      end
-      
     end
 
   end
diff --git a/spec/active_record/multiparameter_attributes_spec.rb b/spec/active_record/multiparameter_attributes_spec.rb
index 23b341b..17032e9 100644
--- a/spec/active_record/multiparameter_attributes_spec.rb
+++ b/spec/active_record/multiparameter_attributes_spec.rb
@@ -6,17 +6,17 @@ describe ValidatesTimeliness::ActiveRecord::MultiparameterAttributes do
   end
 
   it "should convert array for datetime type into datetime string" do
-    time_string = obj.time_array_to_string([2000,2,1,9,10,11], :datetime)
+    time_string = time_array_to_string([2000,2,1,9,10,11], :datetime)
     time_string.should == "2000-02-01 09:10:11"
   end
   
   it "should convert array for date type into date string" do
-    time_string = obj.time_array_to_string([2000,2,1], :date)
+    time_string = time_array_to_string([2000,2,1], :date)
     time_string.should == "2000-02-01"
   end
   
   it "should convert array for time type into time string" do
-    time_string = obj.time_array_to_string([2000,1,1,9,10,11], :time)
+    time_string = time_array_to_string([2000,1,1,9,10,11], :time)
     time_string.should == "09:10:11"
   end
   
@@ -44,5 +44,9 @@ describe ValidatesTimeliness::ActiveRecord::MultiparameterAttributes do
       obj.send(:execute_callstack_for_multiparameter_attributes, @callstack)
     end
   end
+
+  def time_array_to_string(*args)
+    ValidatesTimeliness::ActiveRecord.time_array_to_string(*args)
+  end
   
 end