diff --git a/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Forging.hs b/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Forging.hs
index a494301c48..3613e3b7a4 100644
--- a/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Forging.hs
+++ b/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Forging.hs
@@ -65,7 +65,7 @@ type GenTxs blk mk = SlotNo -> TickedLedgerState blk mk -> IO [Validated (GenTx
 -- For an extensive commentary of the forging loop, see there.
 
 runForge ::
-     forall blk mk.
+     forall blk.
     ( LedgerSupportsProtocol blk )
     => EpochSize
     -> SlotNo
@@ -73,7 +73,7 @@ runForge ::
     -> ChainDB IO blk
     -> [BlockForging IO blk]
     -> TopLevelConfig blk
-    -> GenTxs blk mk
+    -> GenTxs blk DiffMK
     -> IO ForgeResult
 runForge epochSize_ nextSlot opts chainDB blockForging cfg genTxs = do
     putStrLn $ "--> epoch size: " ++ show epochSize_
@@ -168,7 +168,7 @@ runForge epochSize_ nextSlot opts chainDB blockForging cfg genTxs = do
 
         -- Let the caller generate transactions
         -- TODO @js re-enable!
-        txs <- lift $ genTxs currentSlot $ undefined tickedLedgerState
+        txs <- lift $ genTxs currentSlot tickedLedgerState
 
         -- Actually produce the block
         newBlock <- lift $
diff --git a/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Run.hs b/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Run.hs
index 0515680253..b2d0ea669f 100644
--- a/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Run.hs
+++ b/ouroboros-consensus-cardano/src/unstable-cardano-tools/Cardano/Tools/DBSynthesizer/Run.hs
@@ -24,6 +24,7 @@ import           Ouroboros.Consensus.Cardano.Block
 import           Ouroboros.Consensus.Cardano.Node
 import           Ouroboros.Consensus.Config (TopLevelConfig, configStorage)
 import qualified Ouroboros.Consensus.Fragment.InFuture as InFuture (dontCheck)
+import           Ouroboros.Consensus.Ledger.Abstract (DiffMK)
 import qualified Ouroboros.Consensus.Node as Node (stdMkChainDbHasFS)
 import qualified Ouroboros.Consensus.Node.InitStorage as Node
                      (nodeImmutableDbChunkInfo)
@@ -114,7 +115,7 @@ eitherParseJson v = case fromJSON v of
 
 synthesize ::
     (   TopLevelConfig (CardanoBlock StandardCrypto)
-     -> GenTxs (CardanoBlock StandardCrypto) mk
+     -> GenTxs (CardanoBlock StandardCrypto) DiffMK
     )
   -> DBSynthesizerConfig
   -> (CardanoProtocolParams StandardCrypto)