diff --git a/common/AoC.hs b/common/AoC.hs
index cd4fa64..d457242 100644
--- a/common/AoC.hs
+++ b/common/AoC.hs
@@ -13,8 +13,8 @@ oneCompleteResult p s = case readP_to_S (p <* eof) s of
                           [(x, "")] -> Just x
                           _ -> Nothing
 
-splitOnEmptyLines :: String -> [String]
-splitOnEmptyLines = map (intercalate " ")  . filter (not . any null) . groupBy ((==) `on` null) . lines
+splitOnEmptyLines :: String -> [[String]]
+splitOnEmptyLines = filter (not . any null) . groupBy ((==) `on` null) . lines
 
 runAoC :: (Show r1, Show r2) => (String -> i) -> (i -> r1) -> (i -> r2) -> IO ()
 runAoC inputTransform part1 part2 = do
diff --git a/day4/day4.hs b/day4/day4.hs
index fd643af..e219db0 100644
--- a/day4/day4.hs
+++ b/day4/day4.hs
@@ -93,4 +93,4 @@ hasAllRequiredFields = maybe False containsAllFields . fieldNames
           containsAllFields fields = all (`elem` fields) requiredFieldNames
           fieldNames = oneCompleteResult parseFieldNames
 
-main = runAoC (filter hasAllRequiredFields . splitOnEmptyLines) (length) (length . mapMaybe (oneCompleteResult parsePassport))
+main = runAoC (filter hasAllRequiredFields . map (intercalate " ") . splitOnEmptyLines) (length) (length . mapMaybe (oneCompleteResult parsePassport))