diff --git a/lib/validates_timeliness/validator.rb b/lib/validates_timeliness/validator.rb
index 791e3fc..1c1c0d0 100644
--- a/lib/validates_timeliness/validator.rb
+++ b/lib/validates_timeliness/validator.rb
@@ -1,3 +1,4 @@
+#TODO remove deprecated option :equal_to
 module ValidatesTimeliness
 
   class Validator
@@ -7,6 +8,7 @@ module ValidatesTimeliness
 
     RESTRICTION_METHODS = {
       :is_at        => :==,
+      :equal_to     => :==,
       :before       => :<,
       :after        => :>,
       :on_or_before => :<=,
@@ -140,6 +142,12 @@ module ValidatesTimeliness
     end
 
     def validate_options(options)
+      if options.key?(:equal_to)
+        ::ActiveSupport::Deprecation.warn("ValidatesTimeliness :equal_to option is deprecated due to clash with a default Rails option. Use :is_at instead. You will need to fix any I18n error message references to this option date/time attributes now.")
+        options[:is_at] = options.delete(:equal_to)
+        options[:is_at_message] = options.delete(:equal_to_message)
+      end
+
       invalid_for_type = ([:time, :date, :datetime] - [type]).map {|k| "invalid_#{k}_message".to_sym }
       invalid_for_type << :with_date unless type == :time
       invalid_for_type << :with_time unless type == :date