diff --git a/src/Picqer/Financials/Exact/MailMessageAttachment.php b/src/Picqer/Financials/Exact/MailMessageAttachment.php
index 39ac4eed..c5c4ce23 100644
--- a/src/Picqer/Financials/Exact/MailMessageAttachment.php
+++ b/src/Picqer/Financials/Exact/MailMessageAttachment.php
@@ -10,7 +10,7 @@ class MailMessageAttachment extends Model
         'ID',
         'Attachment',
         'AttachmentFileName',
-        'MailMessageId',
+        'MailMessageID',
         'Type'
     ];