diff --git a/db/migrate/20121102142657_create_task_manager_assignables.rb b/db/migrate/20121102142657_create_task_manager_assignables.rb
index <HASH>..<HASH> 100644
--- a/db/migrate/20121102142657_create_task_manager_assignables.rb
+++ b/db/migrate/20121102142657_create_task_manager_assignables.rb
@@ -1,13 +1,13 @@
 class CreateTaskManagerAssignables < ActiveRecord::Migration
   def change
     create_table :task_manager_assignables do |t|
-      t.belongs_to :plan
+      t.belongs_to :target, polymorphic: true
       t.belongs_to :assignee, polymorphic: true
 
       t.timestamps
     end
 
     add_index :task_manager_assignables, [:assignee_id, :assignee_type]
-    add_index :task_manager_assignables, :plan_id
+    add_index :task_manager_assignables, [:target_id, :target_type]
   end
 end
Assignable should have targets with different types