diff --git a/README.md b/README.md
index bb74601..8f85ce2 100644
--- a/README.md
+++ b/README.md
@@ -22,8 +22,8 @@ as a drop-in replacement for the [CodeProject AI ALPR API](https://www.codeproje
 
 **Parameters**
 - upload: (File) The image file to process. (see [Pillow.Image.open()](https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.open) for supported formats)
-- grid_size: (Integer) The grid size to use when no match have been found on the whole image (default: 4)
-- wanted_cells: (String) The wanted cells to use when no match have been found on the whole image (default: all cells)
+- grid_size: (Integer, optional) The grid size to use when no match have been found on the whole image (default: 4)
+- wanted_cells: (String, optional) The wanted cells to use when no match have been found on the whole image (default: all cells)
     - format: ``1,2,3,4,...`` *(comma separated list of integers, max: grid_size^2)*
     - *Example for a grid_size of 3:*
       ```