diff --git a/src/Model/Geometry/Reach.py b/src/Model/Geometry/Reach.py
index ab79afd44e8a3dabc391f62ab39c723d03cc5edb..8246a1a30865c637c3ab69baa580e8572922b0b8 100644
--- a/src/Model/Geometry/Reach.py
+++ b/src/Model/Geometry/Reach.py
@@ -6,6 +6,7 @@ from time import time
 from typing import List
 from copy import deepcopy
 from operator import itemgetter
+from functools import reduce
 
 from tools import flatten
 
@@ -212,7 +213,7 @@ class Reach:
         # Get incomplete guideline
         incomplete = set(
             reduce(
-                lambda acc, h: acc[1] + h[1],
+                lambda acc, h: acc + h,
                 map(
                     lambda l: list(set(l).symmetric_difference(guide_set)),
                     points_name