diff --git a/muk_attachment_lobject/tests/test_attachment.py b/muk_attachment_lobject/tests/test_attachment.py
index b5d4013..fef2e2f 100644
--- a/muk_attachment_lobject/tests/test_attachment.py
+++ b/muk_attachment_lobject/tests/test_attachment.py
@@ -53,4 +53,8 @@ class AttachmentTestCase(common.TransactionCase):
             'name': "Test",
             'datas': base64.b64encode(b"\xff data")})
         self.assertTrue(attach.datas)
+        oid = attach.with_context({'oid': True}).datas
+        self.assertTrue(oid)
+        attach.write({'datas': base64.b64encode(b"\xff data")})
+        self.assertTrue(oid == attach.with_context({'oid': True}).datas)
         attach.unlink()
\ No newline at end of file