diff --git a/CHANGELOG.rdoc b/CHANGELOG.rdoc
index 7363a125..3831e82d 100644
--- a/CHANGELOG.rdoc
+++ b/CHANGELOG.rdoc
@@ -1,5 +1,7 @@
 == master
 
+* Fix mass-assignment sanitization breaking in ActiveRecord 3.0.0 beta5+ [Akira Matsuda]
+
 == 0.9.3 / 2010-06-26
 
 * Allow access to human state / event names in transitions and for the current state
diff --git a/lib/state_machine/integrations/active_record.rb b/lib/state_machine/integrations/active_record.rb
index af771cdf..c163a758 100644
--- a/lib/state_machine/integrations/active_record.rb
+++ b/lib/state_machine/integrations/active_record.rb
@@ -415,12 +415,16 @@ def attributes=(new_attributes, *args)
               if new_record? && !@initialized_state_machines
                 @initialized_state_machines = true
                 
-                if new_attributes
+                ignore = if new_attributes
                   attributes = new_attributes.dup
                   attributes.stringify_keys!
-                  ignore = remove_attributes_protected_from_mass_assignment(attributes).keys
+                  if ::ActiveRecord::VERSION::MAJOR >= 3
+                    sanitize_for_mass_assignment(attributes).keys
+                  else
+                    remove_attributes_protected_from_mass_assignment(attributes).keys
+                  end
                 else
-                  ignore = []
+                  []
                 end
                 
                 initialize_state_machines(:dynamic => false, :ignore => ignore)