diff --git a/bin/hledger-check.hs b/bin/hledger-check.hs
index 73e517230..82bbc0ea5 100755
--- a/bin/hledger-check.hs
+++ b/bin/hledger-check.hs
@@ -87,6 +87,7 @@ import Data.Functor.Identity (Identity(..))
 import Data.List (foldl', groupBy, intercalate, nub, sortOn)
 import Data.List.NonEmpty (NonEmpty(..), nonEmpty, toList)
 import Data.Maybe (fromMaybe, mapMaybe)
+import Data.Monoid ((<>))
 import Data.Time.Calendar (toGregorian)
 import Data.Time.Calendar.OrdinalDate (mondayStartWeek, sundayStartWeek, toOrdinalDate)
 import Data.Text (isPrefixOf, pack, unpack)