diff --git a/activesupport/lib/active_support/time_with_zone.rb b/activesupport/lib/active_support/time_with_zone.rb
index c25c97cfa8..f2a2f3c3db 100644
--- a/activesupport/lib/active_support/time_with_zone.rb
+++ b/activesupport/lib/active_support/time_with_zone.rb
@@ -185,8 +185,11 @@ module ActiveSupport
end
alias_method :rfc822, :rfc2822
- # :db format outputs time in UTC; all others output time in local.
- # Uses TimeWithZone's +strftime+, so %Z and %z work correctly.
+ # Returns a string of the object's date and time.
+ # Accepts an optional format:
+ # * :default - default value, mimics Ruby 1.9 Time#to_s format.
+ # * :db - format outputs time in UTC :db time. See Time#to_formatted_s(:db).
+ # * Any key in Time::DATE_FORMATS can be used. See active_support/core_ext/time/conversions.rb.
def to_s(format = :default)
if format == :db
utc.to_s(format)