diff --git a/src/Entity/Attachments/Attachment.php b/src/Entity/Attachments/Attachment.php
index 5da7e227..9f9b54b8 100644
--- a/src/Entity/Attachments/Attachment.php
+++ b/src/Entity/Attachments/Attachment.php
@@ -25,6 +25,7 @@ namespace App\Entity\Attachments;
 use App\Entity\Base\AbstractNamedDBElement;
 use App\Validator\Constraints\Selectable;
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\Validator\Constraints as Assert;
 use function in_array;
 use InvalidArgumentException;
 use LogicException;
@@ -105,6 +106,7 @@ abstract class Attachment extends AbstractNamedDBElement
      * @ORM\ManyToOne(targetEntity="AttachmentType", inversedBy="attachments_with_type")
      * @ORM\JoinColumn(name="type_id", referencedColumnName="id")
      * @Selectable()
+     * @Assert\NotNull(message="validator.attachment.must_not_be_null")
      */
     protected $attachment_type;
 
diff --git a/translations/validators.en.xlf b/translations/validators.en.xlf
index bbcbee74..8ecde9ad 100644
--- a/translations/validators.en.xlf
+++ b/translations/validators.en.xlf
@@ -215,5 +215,11 @@
         <target>This location can only contain a single part and it is already full!</target>
       </segment>
     </unit>
+    <unit id="4gPskOG" name="validator.attachment.must_not_be_null">
+      <segment>
+        <source>validator.attachment.must_not_be_null</source>
+        <target>You must select an attachment type!</target>
+      </segment>
+    </unit>
   </file>
 </xliff>