diff --git a/cardano-api/internal/Cardano/Api/TxBody.hs b/cardano-api/internal/Cardano/Api/TxBody.hs
index 42b29d10df..a17a98e87e 100644
--- a/cardano-api/internal/Cardano/Api/TxBody.hs
+++ b/cardano-api/internal/Cardano/Api/TxBody.hs
@@ -1799,8 +1799,8 @@ instance Error TxBodyError where
     displayError (TxBodyProtocolParamsConversionError ppces) =
       "Errors in protocol parameters conversion: " ++ displayError ppces
 
-createTransactionBody
-  :: forall era. ShelleyBasedEra era
+createTransactionBody :: ()
+  => ShelleyBasedEra era
   -> TxBodyContent BuildTx era
   -> Either TxBodyError (TxBody era)
 createTransactionBody sbe bc =