diff --git a/db/migrate/20120223110929_change_attachments_container_defaults.rb b/db/migrate/20120223110929_change_attachments_container_defaults.rb
index 39af099f8..f959f4c33 100644
--- a/db/migrate/20120223110929_change_attachments_container_defaults.rb
+++ b/db/migrate/20120223110929_change_attachments_container_defaults.rb
@@ -1,13 +1,25 @@
 class ChangeAttachmentsContainerDefaults < ActiveRecord::Migration
   def self.up
+    # Need to drop the index otherwise the following error occurs in Rails 3.1.3:
+    #
+    # Index name 'temp_index_altered_attachments_on_container_id_and_container_type' on
+    # table 'altered_attachments' is too long; the limit is 64 characters
+    remove_index :attachments, [:container_id, :container_type]
+
     change_column :attachments, :container_id, :integer, :default => nil, :null => true
     change_column :attachments, :container_type, :string, :limit => 30, :default => nil, :null => true
     Attachment.update_all "container_id = NULL", "container_id = 0"
     Attachment.update_all "container_type = NULL", "container_type = ''"
+
+    add_index :attachments, [:container_id, :container_type]
   end
 
   def self.down
+    remove_index :attachments, [:container_id, :container_type]
+
     change_column :attachments, :container_id, :integer, :default => 0, :null => false
     change_column :attachments, :container_type, :string, :limit => 30, :default => "", :null => false
+
+    add_index :attachments, [:container_id, :container_type]
   end
 end