diff --git a/arkindex_worker/worker/metadata.py b/arkindex_worker/worker/metadata.py
index 1147bc2d38b8ed0871669894c299b39970e96fc2..d0995d469de26c51f006a08961f63390ba4ee721 100644
--- a/arkindex_worker/worker/metadata.py
+++ b/arkindex_worker/worker/metadata.py
@@ -109,7 +109,7 @@ class MetaDataMixin(object):
         self,
         element: Element,
         metadata_list: list,
-        worker_version: bool = None,
+        worker_version: str = None,
     ):
         """
         Create multiple metadata on an existing element.
diff --git a/tests/test_elements_worker/test_metadata.py b/tests/test_elements_worker/test_metadata.py
index 4e414809f90e6036bac9b1176bdcd38e2ef8bc52..2a1ff4d4c80fdb9ed37c8f8f2f87e6b9fa6b419b 100644
--- a/tests/test_elements_worker/test_metadata.py
+++ b/tests/test_elements_worker/test_metadata.py
@@ -198,19 +198,22 @@ def test_create_metadata(responses, mock_elements_worker):
     assert metadata_id == "12345678-1234-1234-1234-123456789123"
 
 
-def test_create_metadatabulk(responses, fake_dummy_worker):
+@pytest.mark.parametrize(
+    "worker_version",
+    [(None), (), ("worker_version")],
+)
+def test_create_metadatabulk(fake_dummy_worker, worker_version):
     element = Element({"id": "element_id"})
     metadata_list = [MetaType("text"), "fake_name", "fake_value"]
-    worker_version = "worker_version"
     fake_dummy_worker.api_client.add_response(
         "CreateMetaDataBulk",
         id=element.id,
-        response={"worker_version": "worker_version", "metadata_list": metadata_list},
-        body={"worker_version": "worker_version", "metadata_list": metadata_list},
+        response={"worker_version": worker_version, "metadata_list": metadata_list},
+        body={"worker_version": worker_version, "metadata_list": metadata_list},
     )
     assert fake_dummy_worker.create_metadatabulk(
         element, metadata_list, worker_version
-    ) == {"worker_version": "worker_version", "metadata_list": metadata_list}
+    ) == {"worker_version": worker_version, "metadata_list": metadata_list}
 
     assert len(fake_dummy_worker.api_client.history) == 1
     assert len(fake_dummy_worker.api_client.responses) == 0