diff --git a/haskell/Main.hs b/haskell/Main.hs
index bdd1d98..91de52b 100644
--- a/haskell/Main.hs
+++ b/haskell/Main.hs
@@ -26,7 +26,7 @@ main =
                 , Day3.puzzle
                 , Day4.puzzle
                 ]
-                    <&> \Puzzle{number, parser, parts} ->
+                    <&> \Puzzle{number, parser, parts, extraTests} ->
                         let
                             pt = show number
                             parseFile fp =
@@ -36,6 +36,9 @@ main =
                          in
                             withResource (parseFile $ "../inputs/" <> t <> "/" <> pt) mempty \input ->
                                 testGroup pt $
+                                    (
                                     zip (map show [1 :: Int ..]) parts <&> \(n, pp) ->
                                         goldenVsString n ("../outputs/" <> t <> "/" <> pt <> "/" <> n) $
                                             BL.fromStrict . encodeUtf8 . pp <$> input
+                                    )
+                                        <> [testGroup "extra" extraTests]
diff --git a/haskell/Puzzle.hs b/haskell/Puzzle.hs
index b137bfe..8f252bf 100644
--- a/haskell/Puzzle.hs
+++ b/haskell/Puzzle.hs
@@ -2,10 +2,12 @@ module Puzzle where
 
 import Data.Text (Text)
 import Data.Void
+import Test.Tasty
 import Text.Megaparsec
 
 data Puzzle = forall input. Puzzle
     { number :: Word
     , parser :: Parsec Void Text input
     , parts :: [input -> Text]
+    , extraTests :: [TestTree]
     }
diff --git a/haskell/Puzzles/Day1.hs b/haskell/Puzzles/Day1.hs
index 49b1dd0..74883bb 100644
--- a/haskell/Puzzles/Day1.hs
+++ b/haskell/Puzzles/Day1.hs
@@ -37,6 +37,7 @@ puzzle =
                                 | p' == 0 -> abs c + 1
                                 | otherwise -> abs c
             ]
+        , extraTests = []
         }
 
 data Direction = L | R
diff --git a/haskell/Puzzles/Day2.hs b/haskell/Puzzles/Day2.hs
index 1026180..dbda2e1 100644
--- a/haskell/Puzzles/Day2.hs
+++ b/haskell/Puzzles/Day2.hs
@@ -25,6 +25,7 @@ puzzle =
                 . concatMap
                     (mapMaybe (\n -> guard (isRepetitionN n) $> n) . uncurry enumFromTo)
             ]
+        , extraTests = []
         }
 
 newtype ID = ID Int
diff --git a/haskell/Puzzles/Day3.hs b/haskell/Puzzles/Day3.hs
index e3c484d..a07967e 100644
--- a/haskell/Puzzles/Day3.hs
+++ b/haskell/Puzzles/Day3.hs
@@ -26,6 +26,7 @@ puzzle =
                 . sum
                 . map (digitsToInt . fromMaybe (error "battery list too short") . maxBatteries 12)
             ]
+        , extraTests = []
         }
 
 newtype Bank = Bank (NonEmpty Battery)
diff --git a/haskell/Puzzles/Day4.hs b/haskell/Puzzles/Day4.hs
index 4e8cb15..7685159 100644
--- a/haskell/Puzzles/Day4.hs
+++ b/haskell/Puzzles/Day4.hs
@@ -27,6 +27,7 @@ puzzle =
                 . unfoldr ((\r -> guard (fst r /= 0) $> r) . (removeAccessibleRolls <<<<$>>>>) . findAccessible)
                 . addCoords
             ]
+        , extraTests = []
         }
 
 addCoords :: (Num a, Enum a) => [[c]] -> [[(V2 a, c)]]