diff --git a/shared/data_store/get.py b/shared/data_store/get.py
index d0b03a7..f975cf6 100644
--- a/shared/data_store/get.py
+++ b/shared/data_store/get.py
@@ -15,11 +15,12 @@ def get(
     """Get buffer from bucket in MinIO."""
     assert isinstance(client, Minio)
     assert isinstance(object_name, str)
+    assert 'MINIO_BUCKET_NAME' in os.environ
     bucket_name = os.getenv('MINIO_BUCKET_NAME')
     # get buffer
     try:
         response = client.get_object(
-            bucket_name=bucket_name,
+            bucket_name=bucket_name,  # type: ignore
             object_name=object_name,
         )
         assert response.status == 200