diff --git a/admin/templates/shop-product/product-edit.php b/admin/templates/shop-product/product-edit.php
index b5da719..1e73bb2 100644
--- a/admin/templates/shop-product/product-edit.php
+++ b/admin/templates/shop-product/product-edit.php
@@ -589,7 +589,7 @@ ob_start();
             <option value="">wybierz produkt...</option>
             <? foreach ($this->products as $key => $val) : ?>
               <? if ($key != $this->product['id']) : ?>
-                <option value="<?= $key; ?>" <? if (in_array($key, $this->product['products_related'])) : ?>selected<? endif; ?>><?= $val; ?></option>
+                <option value="<?= $key; ?>" <? if ( is_array( $this -> product['products_related'] ) and in_array($key, $this->product['products_related'])) : ?>selected<? endif; ?>><?= $val; ?></option>
               <? endif; ?>
             <? endforeach; ?>
           </select>