diff --git a/app/Observers/PurchaseOrderObserver.php b/app/Observers/PurchaseOrderObserver.php
index ff3eb89ef99d..4af8e1722ab5 100644
--- a/app/Observers/PurchaseOrderObserver.php
+++ b/app/Observers/PurchaseOrderObserver.php
@@ -1,5 +1,13 @@
 <?php
-
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www.elastic.co/licensing/elastic-license
+ */
 
 namespace App\Observers;
 
diff --git a/app/Policies/PurchaseOrderPolicy.php b/app/Policies/PurchaseOrderPolicy.php
index 78656bb21b63..39cb49327eb0 100644
--- a/app/Policies/PurchaseOrderPolicy.php
+++ b/app/Policies/PurchaseOrderPolicy.php
@@ -1,5 +1,13 @@
 <?php
-
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2022. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www.elastic.co/licensing/elastic-license
+ */
 
 namespace App\Policies;
 
diff --git a/database/migrations/2022_05_28_234651_create_purchase_orders_table.php b/database/migrations/2022_05_28_234651_create_purchase_orders_table.php
index 1229e46fe622..14cdf0c6e5f5 100644
--- a/database/migrations/2022_05_28_234651_create_purchase_orders_table.php
+++ b/database/migrations/2022_05_28_234651_create_purchase_orders_table.php
@@ -104,6 +104,11 @@ class CreatePurchaseOrdersTable extends Migration
 
             $table->datetime('last_viewed')->nullable();
 
+            $table->foreign('client_id')->references('id')->on('clients')->onDelete('cascade')->onUpdate('cascade');
+            $table->foreign('company_id')->references('id')->on('companies')->onDelete('cascade')->onUpdate('cascade');
+            $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade')->onUpdate('cascade');
+            $table->index(['company_id', 'deleted_at']);
+
             $table->softDeletes();
             $table->timestamps();