diff --git a/2020/day4/day4.hs b/2020/day4/day4.hs
index b2baa8a..36b935f 100644
--- a/2020/day4/day4.hs
+++ b/2020/day4/day4.hs
@@ -89,11 +89,6 @@ parseFieldNames = spaceSeparated parseFieldName
 parsePassport :: ReadP [Field]
 parsePassport = spaceSeparated parseField
 
-oneCompleteResult :: ReadP a -> String -> Maybe a
-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
 
diff --git a/common/AoC.hs b/common/AoC.hs
index b687673..bdc48cf 100644
--- a/common/AoC.hs
+++ b/common/AoC.hs
@@ -1,9 +1,16 @@
 module AoC where
 
+import Text.ParserCombinators.ReadP
+
 (.:) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
 f .: g = (f .) . g
 infixl 8 .:
 
+oneCompleteResult :: ReadP a -> String -> Maybe a
+oneCompleteResult p s = case readP_to_S (p <* eof) s of
+                          [(x, "")] -> Just x
+                          _ -> Nothing
+
 runAoC :: (Show r1, Show r2) => (String -> i) -> (i -> r1) -> (i -> r2) -> IO ()
 runAoC inputTransform part1 part2 = do
     contents <- inputTransform <$> getContents