diff --git a/common/AoC.hs b/common/AoC.hs
index bdc48cf..cd4fa64 100644
--- a/common/AoC.hs
+++ b/common/AoC.hs
@@ -1,5 +1,7 @@
 module AoC where
 
+import Data.Function (on)
+import Data.List (groupBy, intercalate)
 import Text.ParserCombinators.ReadP
 
 (.:) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
@@ -11,6 +13,9 @@ 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
+
 runAoC :: (Show r1, Show r2) => (String -> i) -> (i -> r1) -> (i -> r2) -> IO ()
 runAoC inputTransform part1 part2 = do
     contents <- inputTransform <$> getContents
diff --git a/day4/day4.hs b/day4/day4.hs
index 36b935f..fd643af 100644
--- a/day4/day4.hs
+++ b/day4/day4.hs
@@ -3,8 +3,6 @@ import AoC
 import Control.Applicative ((<|>))
 import Control.Monad (guard, mfilter)
 import Data.Char (isDigit)
-import Data.Function (on)
-import Data.List (groupBy, intercalate)
 import Data.Maybe (mapMaybe)
 import Text.ParserCombinators.ReadP
 import Text.Read (readMaybe)
@@ -89,9 +87,6 @@ parseFieldNames = spaceSeparated parseFieldName
 parsePassport :: ReadP [Field]
 parsePassport = spaceSeparated parseField
 
-splitOnEmptyLines :: String -> [String]
-splitOnEmptyLines = map (intercalate " ") . filter (not . any null) . groupBy ((==) `on` null) . lines
-
 hasAllRequiredFields :: String -> Bool
 hasAllRequiredFields = maybe False containsAllFields . fieldNames
     where requiredFieldNames = ["byr", "iyr", "eyr", "hgt", "hcl", "ecl", "pid"]