diff --git a/ouroboros-consensus/bench/mempool-bench/Main.hs b/ouroboros-consensus/bench/mempool-bench/Main.hs
index dfce74f113..f439c2b48e 100644
--- a/ouroboros-consensus/bench/mempool-bench/Main.hs
+++ b/ouroboros-consensus/bench/mempool-bench/Main.hs
@@ -16,6 +16,7 @@ import qualified Control.Tracer as Tracer
 import           Data.Aeson
 import qualified Data.ByteString.Lazy as BL
 import qualified Data.Csv as Csv
+import           Data.Foldable (foldMap')
 import           Data.Maybe (fromMaybe)
 import           Data.Set ()
 import qualified Data.Text as Text
@@ -139,7 +140,7 @@ openMempoolWithCapacityFor cmds =
                              }
   where
     capacityRequiredByCmds = Mempool.mkCapacityBytesOverride totalTxsSize
-      where totalTxsSize = foldMap TestBlock.txSize $ getCmdsTxs cmds
+      where totalTxsSize = foldMap' TestBlock.txSize $ getCmdsTxs cmds
 
 mkNTryAddTxs :: Int -> [MempoolCmd TestBlock.TestBlock]
 mkNTryAddTxs 0 = []