diff --git a/python_scripts/add_trees_to_open_street_map/add_trees.py b/python_scripts/add_trees_to_open_street_map/add_trees.py
index 32e10df96cac977d7a875e977bc95039b68a289f..35fa8a5fdae96f5fd04fd69438bc4eca73727cca 100644
--- a/python_scripts/add_trees_to_open_street_map/add_trees.py
+++ b/python_scripts/add_trees_to_open_street_map/add_trees.py
@@ -57,7 +57,7 @@ def load_region(wkt_polygon: str):
     return region, bounds
 
 
-def get_basename(bounds):
+def get_basename(bounds: Bounds):
     return f'{bounds.S}__{bounds.N}__{bounds.W}__{bounds.E}_{TREE_DISTANCE}m'.replace('.', '_')