diff --git a/aspa/test.py b/aspa/test.py
index 4b2fc98..8f8019c 100644
--- a/aspa/test.py
+++ b/aspa/test.py
@@ -118,6 +118,7 @@ def test_all_valid(self):
 
     def test_valid_edge(self):
         self.assertFalse(self.validator.is_aspa_invalid_upstream(64530, [64520, 64510]))
+        self.assertFalse(self.validator.is_aspa_invalid_upstream(64530, [64520, 64521]))
         self.assertFalse(self.validator.is_aspa_invalid_upstream(64530, [64520]))
         self.assertFalse(self.validator.is_aspa_invalid_upstream(64520, [64510]))