diff --git a/random_material_assigners/random_material_assigner_per_face_new_features.py b/random_material_assigners/random_material_assigner_per_face_new_features.py
index 873c9bc..c9e9956 100644
--- a/random_material_assigners/random_material_assigner_per_face_new_features.py
+++ b/random_material_assigners/random_material_assigner_per_face_new_features.py
@@ -159,6 +159,7 @@ def randomize( self, context ):
 
         ## Distribute materials by loose parts
         elif self.assign_method == 'Loose Parts':
+            bm.verts.ensure_lookup_table()
             vert_indices = [ vert.index for vert in bm.verts ]  # Reference all vertex indices
 
             for vert in vert_indices: