diff --git a/src/Algorithm.hs b/src/Algorithm.hs
index 0a17048a7..023347356 100644
--- a/src/Algorithm.hs
+++ b/src/Algorithm.hs
@@ -4,7 +4,6 @@ module Algorithm where
 import Control.Applicative (liftA2)
 import Control.Monad (guard, join)
 import Control.Monad.Free.Freer
-import Data.Function (on)
 import Data.Functor.Classes
 import Data.List.NonEmpty (NonEmpty(..))
 import Data.Maybe