diff --git a/core/collections.nom b/core/collections.nom
index 9c7e8d0..2af7605 100644
--- a/core/collections.nom
+++ b/core/collections.nom
@@ -29,6 +29,7 @@ test:
     assume ((%list::last) == 5)
     %list::remove index 1
     assume ((%list::first) == 2)
+    assume (([1, 2] + [3, 4]) == [1, 2, 3, 4])
 
 # Dict functionality
 test: