Parsing date from PayPal fails

I have a scenario where this code works on Ruby 1.8.6 on my local
environment but my hosting provider uses Ruby 1.8.5, and it causes an
exception.

The code in questions is:

dt = DateTime.parse(params[:payment_date])

and the date looks like: 09:45:21 Apr 30, 2007 PDT

Has anyone else run into this? Is there a prescribed way around it?

Exception follows:

ArgumentError (3 elements of civil date are necessary):
/usr/lib/ruby/1.8/date.rb:1214:in new_with_hash' /usr/lib/ruby/1.8/date.rb:1258:inparse’
/app/controllers/ipn_controller.rb:12:in paypal_ipn' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/base.rb:1095:insend’
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/
action_controller/base.rb:1095:in perform_action_without_filters' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/filters.rb:632:incall_filter’
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/
action_controller/filters.rb:619:in perform_action_without_benchmark' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/benchmarking.rb:66:inperform_action_without_rescue’
/usr/lib/ruby/1.8/benchmark.rb:293:in measure' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/benchmarking.rb:66:inperform_action_without_rescue’
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/
action_controller/rescue.rb:83:in perform_action' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/base.rb:430:insend’
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/
action_controller/base.rb:430:in process_without_filters' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/filters.rb:624:inprocess_without_session_management_support’
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/
action_controller/session_management.rb:114:in process' /usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/ action_controller/base.rb:330:inprocess’
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:in
dispatch' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb: 78:inprocess’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:
76:in synchronize' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb: 76:inprocess’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:618:in
process_client' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:ineach’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in
process_client' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:inrun’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
initialize' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:innew’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
run' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:ininitialize’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in
new' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:inrun’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/
configurator.rb:271:in run' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/ configurator.rb:270:ineach’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/
configurator.rb:270:in run' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:inrun’
/usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:
211:in run' /usr/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243 /usr/bin/mongrel_rails:18:inload’
/usr/bin/mongrel_rails:18