diff --git a/rmf_building_map_tools/building_map/floor.py b/rmf_building_map_tools/building_map/floor.py
index 4392e568..f6cbe71f 100644
--- a/rmf_building_map_tools/building_map/floor.py
+++ b/rmf_building_map_tools/building_map/floor.py
@@ -141,7 +141,7 @@ def triangulate_polygon(self, polygon, triangles):
                 # to be clipped to lie within the original floor polygon
                 # for example, if a long triangle crossed a concave region
                 # and you end up with >=1 polygons and >=1 points or edges.
-                for item in geom:
+                for item in geom.geoms:
                     if item.geom_type == 'Polygon':
                         self.triangulate_polygon(item, triangles)