diff --git a/bench/Main.hs b/bench/Main.hs
index bed63496..6f4d73bb 100644
--- a/bench/Main.hs
+++ b/bench/Main.hs
@@ -18,6 +18,7 @@ import Criterion.Main
 import Data.Dependent.Map (DMap)
 import qualified Data.Dependent.Map as DMap
 import Data.Dependent.Sum
+import Data.Functor (void)
 import Data.Functor.Misc
 import Data.IORef
 import Data.Maybe (fromJust)