diff --git a/db/migrate/20110520150544_remove_categories_with_invalid_type.rb b/db/migrate/20110520150544_remove_categories_with_invalid_type.rb
index 53f44d7..214b6e2 100644
--- a/db/migrate/20110520150544_remove_categories_with_invalid_type.rb
+++ b/db/migrate/20110520150544_remove_categories_with_invalid_type.rb
@@ -2,14 +2,17 @@ class RemoveCategoriesWithInvalidType < ActiveRecord::Migration
 
   def self.remove_invalid(category)
     if category.class != ProductCategory && !category.class.ancestors.include?(ProductCategory)
-      category.destroy
+      execute("update categories set type='ProductCategory' where id=#{category.id}")
     else
       category.children.map { |child| remove_invalid(child) }
     end
   end
 
   def self.up
-    ProductCategory.all.map { |category| remove_invalid(category)}
+    select_all("SELECT id from categories WHERE type = 'ProductCategory'").each do |product_category|
+      category = ProductCategory.find(product_category['id'])
+      remove_invalid(category)
+    end
   end
 
   def self.down
diff --git a/db/schema.rb b/db/schema.rb
index 3ee7061..3ac08bd 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -9,7 +9,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20110316171323) do
+ActiveRecord::Schema.define(:version => 20110520150544) do
 
   create_table "action_tracker", :force => true do |t|
     t.integer  "user_id"
diff --git a/test/functional/categories_controller_test.rb b/test/functional/categories_controller_test.rb
index e11112e..9f1121d 100644
--- a/test/functional/categories_controller_test.rb
+++ b/test/functional/categories_controller_test.rb
@@ -170,7 +170,7 @@ class CategoriesControllerTest < Test::Unit::TestCase
   should 'use parent\'s type to determine subcategory\'s type' do
     parent = ProductCategory.create!(:name => 'Sample category', :environment => Environment.default)
     post :new, :parent_id => parent.id, :parent_type => parent.class.name, :category => {:name => 'Subcategory'}
-    sub = Category.last
+    sub = ProductCategory.find_by_name('Subcategory')
     assert_equal parent.class, sub.class
   end
 
--
libgit2 0.21.2