diff --git a/db/migrate/20110211204804_unique_index_post_visibilities.rb b/db/migrate/20110211204804_unique_index_post_visibilities.rb
index 2d2bbebc9..70b7f2164 100644
--- a/db/migrate/20110211204804_unique_index_post_visibilities.rb
+++ b/db/migrate/20110211204804_unique_index_post_visibilities.rb
@@ -22,6 +22,8 @@ class UniqueIndexPostVisibilities < ActiveRecord::Migration
     end
     execute("DELETE FROM `post_visibilities` WHERE `post_visibilities`.id IN (#{undesired_ids.join(",")});") unless undesired_ids.empty?
 
+    new_result = execute(sql)
+    raise "Not all violating visibilities deleted" unless new_result.to_a.empty?
 
     remove_index :post_visibilities, [:aspect_id, :post_id]
     add_index :post_visibilities, [:aspect_id, :post_id], :unique => true