diff --git a/rmf_building_map_tools/building_map/floor.py b/rmf_building_map_tools/building_map/floor.py
index f6cbe71f5..6449e1f0d 100644
--- a/rmf_building_map_tools/building_map/floor.py
+++ b/rmf_building_map_tools/building_map/floor.py
@@ -133,7 +133,7 @@ def triangulate_polygon(self, polygon, triangles):
                         plt.plot(poly_x, poly_y, 'b', linewidth=4)
 
             elif geom.geom_type == 'MultiPolygon':
-                for poly in list(geom):
+                for poly in list(geom.geoms):
                     self.triangulate_polygon(poly, triangles)
 
             elif geom.geom_type == 'GeometryCollection':