diff --git a/src/openforms/submissions/models/submission.py b/src/openforms/submissions/models/submission.py
index 969ff8c7b6..8592e308c2 100644
--- a/src/openforms/submissions/models/submission.py
+++ b/src/openforms/submissions/models/submission.py
@@ -714,7 +714,7 @@ def get_co_signer(self) -> str:
     def get_attachments(self) -> SubmissionFileAttachmentQuerySet:
         from .submission_files import SubmissionFileAttachment
 
-        return SubmissionFileAttachment.objects.for_submission(self)
+        return SubmissionFileAttachment.objects.for_submission(self).order_by("pk")
 
     @property
     def attachments(self) -> SubmissionFileAttachmentQuerySet: