diff --git a/db/migrate/20180613045614_add_contacts_and_domains_uuid_uniq_constraint.rb b/db/migrate/20180613045614_add_contacts_and_domains_uuid_uniq_constraint.rb
index 99e9b823d..32b8fb090 100644
--- a/db/migrate/20180613045614_add_contacts_and_domains_uuid_uniq_constraint.rb
+++ b/db/migrate/20180613045614_add_contacts_and_domains_uuid_uniq_constraint.rb
@@ -1,3 +1,4 @@
+# Unique constraint is needed to prevent accidental duplicate values in fixtures to appear in DB
 class AddContactsAndDomainsUuidUniqConstraint < ActiveRecord::Migration
   def up
     execute <<-SQL