diff --git a/backend/api/views/function.py b/backend/api/views/function.py
index cc692749b..e906c450d 100644
--- a/backend/api/views/function.py
+++ b/backend/api/views/function.py
@@ -230,6 +230,7 @@ def image(self, request, *args, **kwargs):
                 status=status.HTTP_404_NOT_FOUND,
             )
 
-        # TODO we love hard-coded size, see also api.views.utils.PermissionMixin._download_remote_file
-        response = CustomFileResponse(streaming_content=(chunk for chunk in function_image.file.chunks(512 * 1024)))
+        response = CustomFileResponse(
+            streaming_content=(chunk for chunk in function_image.file.chunks(self.chunk_size))
+        )
         return response
diff --git a/backend/api/views/utils.py b/backend/api/views/utils.py
index baea84e41..48605757a 100644
--- a/backend/api/views/utils.py
+++ b/backend/api/views/utils.py
@@ -66,6 +66,7 @@ def set_headers(self, filelike):
 class PermissionMixin(object):
     authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES + [BasicAuthentication]
     permission_classes = [IsAuthorized]
+    chunk_size = 512 * 1024
 
     def check_access(self, channel_name: str, user, asset, is_proxied_request: bool) -> None:
         """Returns true if API consumer is allowed to access data.
@@ -142,7 +143,7 @@ def _download_remote_file(self, channel_name: str, owner: str, url: str) -> djan
             headers={HTTP_HEADER_PROXY_ASSET: "True"},
         )
         response = CustomFileResponse(
-            streaming_content=(chunk for chunk in proxy_response.iter_content(512 * 1024)),
+            streaming_content=(chunk for chunk in proxy_response.iter_content(self.chunk_size)),
             status=proxy_response.status_code,
         )