diff --git a/controllers/admin/AdminCustomerThreadsController.php b/controllers/admin/AdminCustomerThreadsController.php
index 8d3d68d5c..b678cc1d4 100644
--- a/controllers/admin/AdminCustomerThreadsController.php
+++ b/controllers/admin/AdminCustomerThreadsController.php
@@ -458,7 +458,7 @@ class AdminCustomerThreadsControllerCore extends AdminController
 
 		$extension = false;
 		foreach ($extensions as $key => $val)
-			if (substr($filename, -4) == $key || substr($filename, -5) == $key)
+			if (substr(Tools::strtolower($filename), -4) == $key || substr(Tools::strtolower($filename), -5) == $key)
 			{
 				$extension = $val;
 				break;
diff --git a/controllers/front/ContactController.php b/controllers/front/ContactController.php
index 713d8bd1d..598258a8d 100644
--- a/controllers/front/ContactController.php
+++ b/controllers/front/ContactController.php
@@ -57,7 +57,7 @@ class ContactControllerCore extends FrontController
 				$this->errors[] = Tools::displayError('Please select a subject from the list provided. ');
 			else if (!empty($_FILES['fileUpload']['name']) && $_FILES['fileUpload']['error'] != 0)
 				$this->errors[] = Tools::displayError('An error occurred during the file-upload process.');
-			else if (!empty($_FILES['fileUpload']['name']) && !in_array(substr($_FILES['fileUpload']['name'], -4), $extension) && !in_array(substr($_FILES['fileUpload']['name'], -5), $extension))
+			else if (!empty($_FILES['fileUpload']['name']) && !in_array(substr(Tools::strtolower($_FILES['fileUpload']['name']), -4), $extension) && !in_array(substr(Tools::strtolower($_FILES['fileUpload']['name']), -5), $extension))
 				$this->errors[] = Tools::displayError('Bad file extension');
 			else
 			{