diff --git a/aoc2024/Day21.newt.golden b/aoc2024/Day21.newt.golden
index e740b44..08cb442 100644
--- a/aoc2024/Day21.newt.golden
+++ b/aoc2024/Day21.newt.golden
@@ -1,8 +1,8 @@
 aoc2024/day21/eg.txt
-(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))
+[(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))]
 part1 126384
 part2 154115708116294
 aoc2024/day21/input.txt
-(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))
+[(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))]
 part1 248108
 part2 303836969158972
diff --git a/aoc2024/Day21monad.newt.golden b/aoc2024/Day21monad.newt.golden
index e740b44..08cb442 100644
--- a/aoc2024/Day21monad.newt.golden
+++ b/aoc2024/Day21monad.newt.golden
@@ -1,8 +1,8 @@
 aoc2024/day21/eg.txt
-(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))
+[(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))]
 part1 126384
 part2 154115708116294
 aoc2024/day21/input.txt
-(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))
+[(0, (3, 1)), (1, (2, 0)), (2, (2, 1)), (3, (2, 2)), (4, (1, 0)), (5, (1, 1)), (6, (1, 2)), (7, (0, 0)), (8, (0, 1)), (9, (0, 2)), (A, (3, 2))]
 part1 248108
 part2 303836969158972
diff --git a/src/Prelude.newt b/src/Prelude.newt
index 9e88a79..90fa041 100644
--- a/src/Prelude.newt
+++ b/src/Prelude.newt
@@ -828,7 +828,7 @@ instance ∀ a b. {{Show a}} {{Show b}} → Show (a × b) where
   show (a,b) = "(" ++ show a ++ ", " ++ show b ++ ")"
 
 instance ∀ a. {{Show a}} → Show (List a) where
-  show xs = joinBy ", " $ map show xs
+  show xs = "[" ++ (joinBy ", " $ map show xs) ++ "]"
 
 -- For now, I'm not having the compiler do this automatically
 
diff --git a/tests/Possible.newt.fail b/tests/Possible.newt.fail
index da2b20d..ab1832b 100644
--- a/tests/Possible.newt.fail
+++ b/tests/Possible.newt.fail
@@ -1,7 +1,7 @@
 *** Process tests/Possible.newt
 module Prelude
 module Possible
-ERROR at tests/Possible.newt:6:5--6:8: possible constructors: Prelude.Z, Prelude.S
+ERROR at tests/Possible.newt:6:5--6:8: possible constructors: [Prelude.Z, Prelude.S]
   
   foo : Nat → Nat
   foo ()