diff --git a/src/Entity/Category.php b/src/Entity/Category.php
index 1ae4935c..858b2ef5 100644
--- a/src/Entity/Category.php
+++ b/src/Entity/Category.php
@@ -50,8 +50,8 @@ class Category extends PartsContainingDBElement
     protected $parts;
 
     /**
-     * @var bool
-     * @ORM\Column(type="boolean")
+     * @var string
+     * @ORM\Column(type="string")
      */
     protected $partname_hint;
 
diff --git a/src/Entity/NamedDBElement.php b/src/Entity/NamedDBElement.php
index 9b92a0a2..0b832855 100644
--- a/src/Entity/NamedDBElement.php
+++ b/src/Entity/NamedDBElement.php
@@ -69,7 +69,7 @@ abstract class NamedDBElement extends DBElement
 
     /**
      * Returns the last time when the element was modified.
-     * @return string The time of the last edit.
+     * @return \DateTime The time of the last edit.
      */
     public function getLastModified() : \DateTime
     {
@@ -78,13 +78,10 @@ abstract class NamedDBElement extends DBElement
 
     /**
      * Returns the date/time when the element was created.
-     * @param $formatted bool When true, the date gets formatted with the locale and timezone settings.
-     *       When false, the raw value from the DB is returned.
-     * @return string The creation time of the part.
+     * @return \DateTime The creation time of the part.
      */
-    public function getDatetimeAdded() : \DateTime
+    public function getAddedDate() : \DateTime
     {
-        //TODO
         return $this->addedDate;
     }
 
@@ -102,6 +99,7 @@ abstract class NamedDBElement extends DBElement
      *          So you don't have to do this yourself.
      *
      * @param string $new_name      the new name
+     * @return self
      */
     public function setName(string $new_name) : self
     {
diff --git a/templates/show_part_info.html.twig b/templates/show_part_info.html.twig
index 0fd69b45..ec075be1 100644
--- a/templates/show_part_info.html.twig
+++ b/templates/show_part_info.html.twig
@@ -213,7 +213,7 @@
 
                     <div class="form-group">
                         <label>{% trans %}lastModified{% endtrans %}:</label>
-                        <p>{{ part.lastModified | date }}
+                        <p>{{ part.addedDate | date }}
                             {# {if !empty($last_modified_user)} {% trans %}by{% endtrans %}
                             {if $can_visit_user}
                             <a href="{$relative_path}user_info.php?uid={$last_modified_user_id}">{$last_modified_user}</a>