diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9a43851..809a14b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # CHANGELOG
 
+## Version [3.9.1] (2024-01-02)
+
+### Refactor
+
+-   Remove strtolower check when validating value of UniformeProductnaam.
+-   Remove conversion to lowercase of meta '_owc_pdc_upl_naam' when validating the values.
+
 ## Version [3.9] (2023-10-27)
 
 ### Feat
diff --git a/pdc-base.php b/pdc-base.php
index 3e9be72..3dcd71e 100644
--- a/pdc-base.php
+++ b/pdc-base.php
@@ -4,7 +4,7 @@
  * Plugin Name:       Yard | PDC Base
  * Plugin URI:        https://www.openwebconcept.nl/
  * Description:       Acts as foundation for other PDC related content plugins. This plugin implements actions to allow for other plugins to add and/or change Custom Posttypes, Metaboxes, Taxonomies, en Posts 2 posts relations.
- * Version:           3.9
+ * Version:           3.9.1
  * Author:            Yard | Digital Agency
  * Author URI:        https://www.yard.nl/
  * License:           GPL-3.0
diff --git a/src/Base/Foundation/Plugin.php b/src/Base/Foundation/Plugin.php
index 014767f..f79e98c 100644
--- a/src/Base/Foundation/Plugin.php
+++ b/src/Base/Foundation/Plugin.php
@@ -19,7 +19,7 @@ class Plugin
      *
      * @var string
      */
-    public const VERSION = '3.9';
+    public const VERSION = '3.9.1';
 
     /**
      * Path to the root of the plugin.
diff --git a/src/Base/UPL/CorrectItems.php b/src/Base/UPL/CorrectItems.php
index f1e5197..2d3d860 100644
--- a/src/Base/UPL/CorrectItems.php
+++ b/src/Base/UPL/CorrectItems.php
@@ -6,7 +6,6 @@ class CorrectItems extends UPL
 {
     public function handle()
     {
-        $this->validateUPLNames();
         $this->prepareItems();
         $correctItems = $this->compareCorrectItems();
 
@@ -23,7 +22,7 @@ public function compareCorrectItems(): array
     protected function compareCorrectItem($item): bool
     {
         foreach ($this->uplOptions as $option) {
-            if ($item['uplName'] !== strtolower($option['UniformeProductnaam']['value']) || strtolower($item['uplUrl']) !== strtolower($option['URI']['value'])) {
+            if ($option['UniformeProductnaam']['value'] !== $item['uplName'] || strtolower($item['uplUrl']) !== strtolower($option['URI']['value'])) {
                 continue;
             }
 
diff --git a/src/Base/UPL/IncorrectItems.php b/src/Base/UPL/IncorrectItems.php
index c9b970e..952fd87 100644
--- a/src/Base/UPL/IncorrectItems.php
+++ b/src/Base/UPL/IncorrectItems.php
@@ -6,7 +6,6 @@ class IncorrectItems extends UPL
 {
     public function handle()
     {
-        $this->validateUPLNames();
         $this->prepareItems();
         $incorrectItems = $this->compareIncorrectItems();
 
@@ -23,7 +22,7 @@ public function compareIncorrectItems(): array
     protected function compareIncorrectItem($item): bool
     {
         foreach ($this->uplOptions as $option) {
-            if ($item['uplName'] === strtolower($option['UniformeProductnaam']['value']) && strtolower($item['uplUrl']) === strtolower($option['URI']['value'])) {
+            if ($option['UniformeProductnaam']['value'] === $item['uplName'] && strtolower($item['uplUrl']) === strtolower($option['URI']['value'])) {
                 return false;
             }
         }
diff --git a/src/Base/UPL/UPL.php b/src/Base/UPL/UPL.php
index f989d7c..0217a96 100644
--- a/src/Base/UPL/UPL.php
+++ b/src/Base/UPL/UPL.php
@@ -4,40 +4,15 @@
 
 class UPL
 {
+    protected array $items;
+    protected array $uplOptions;
+
     public function __construct(array $items, array $options)
     {
         $this->items = $items;
         $this->uplOptions = $options;
     }
 
-    protected function validateUPLNames(): void
-    {
-        foreach ($this->items as $item) {
-            $uplName = get_post_meta($item->ID, '_owc_pdc_upl_naam', true);
-
-            if (empty($uplName) || ctype_lower($uplName)) {
-                continue;
-            }
-
-            $this->UPLNameToLowerCase($item, $uplName);
-        }
-    }
-
-    /**
-     * Update post meta when value is not in lowercase.
-     * Post meta should be in lowercase so let's fix this in advance.
-     */
-    protected function UPLNameToLowerCase(\WP_Post $item, string $uplName): string
-    {
-        $result = update_post_meta($item->ID, '_owc_pdc_upl_naam', strtolower($uplName));
-
-        if (! $result) {
-            return $uplName;
-        }
-
-        return strtolower($uplName);
-    }
-
     protected function prepareItems(): void
     {
         $this->items = array_map(function ($item) {