diff --git a/scripts/build_bus_regions.py b/scripts/build_bus_regions.py
index 89765ed9..b6d2d129 100644
--- a/scripts/build_bus_regions.py
+++ b/scripts/build_bus_regions.py
@@ -62,7 +62,7 @@ def save_to_geojson(s, fn):
     s.to_file(fn, driver='GeoJSON', schema=schema)
 
 
-def voronoi_partition_pts(points, outline, no_multipolygons=False):
+def voronoi_partition_pts(points, outline):
     """
     Compute the polygons of a voronoi partition of `points` within the
     polygon `outline`. Taken from