diff --git a/cabal.project b/cabal.project
index 704c8b84943..d6be300be45 100644
--- a/cabal.project
+++ b/cabal.project
@@ -42,6 +42,7 @@ test-show-details: streaming
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/cardano-base
+  -- update tag and sha256 after merging https://github.com/input-output-hk/cardano-base/pull/280/commits
   tag: 631cb6cf1fa01ab346233b610a38b3b4cba6e6ab
   --sha256: 0944wg2nqazmhlmsynwgdwxxj6ay0hb9qig9l128isb2cjia0hlp
   subdir:
diff --git a/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/Data.hs b/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/Data.hs
index 1d6d287d83f..5ee91c09c4a 100644
--- a/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/Data.hs
+++ b/eras/alonzo/impl/src/Cardano/Ledger/Alonzo/Data.hs
@@ -54,6 +54,7 @@ import Cardano.Binary
     withSlice,
   )
 import Cardano.Crypto.Hash.Class (HashAlgorithm)
+import Cardano.HeapWords (HeapWords (..), heapWords0, heapWords1)
 import Cardano.Ledger.Alonzo.Era
 import Cardano.Ledger.Alonzo.Language (Language (..))
 import Cardano.Ledger.Alonzo.Scripts (AlonzoScript (..), validScript)
diff --git a/eras/shelley/impl/src/Cardano/Ledger/Shelley/TxBody.hs b/eras/shelley/impl/src/Cardano/Ledger/Shelley/TxBody.hs
index 7b70b4618a5..c62169eb938 100644
--- a/eras/shelley/impl/src/Cardano/Ledger/Shelley/TxBody.hs
+++ b/eras/shelley/impl/src/Cardano/Ledger/Shelley/TxBody.hs
@@ -72,6 +72,7 @@ import Cardano.Binary
     encodeListLen,
   )
 import qualified Cardano.Crypto.Hash.Class as HS
+import Cardano.HeapWords (HeapWords (..))
 import Cardano.Ledger.Address (Addr (..), RewardAcnt (..))
 import Cardano.Ledger.AuxiliaryData (AuxiliaryDataHash)
 import Cardano.Ledger.BaseTypes (StrictMaybe (..), Url)
@@ -109,7 +110,6 @@ import Cardano.Ledger.Shelley.PoolParams
 import Cardano.Ledger.Slot (SlotNo (..))
 import Cardano.Ledger.TxIn (TxIn)
 import Cardano.Ledger.Val (DecodeNonNegative (..))
-import Cardano.Prelude (HeapWords (..))
 import Control.DeepSeq (NFData (rnf))
 import qualified Data.ByteString.Lazy as BSL
 import Data.ByteString.Short (ShortByteString, pack)
diff --git a/libs/cardano-ledger-core/src/Cardano/Ledger/Coin.hs b/libs/cardano-ledger-core/src/Cardano/Ledger/Coin.hs
index e384ca993ec..d4e670762da 100644
--- a/libs/cardano-ledger-core/src/Cardano/Ledger/Coin.hs
+++ b/libs/cardano-ledger-core/src/Cardano/Ledger/Coin.hs
@@ -22,8 +22,8 @@ module Cardano.Ledger.Coin
 where
 
 import Cardano.Binary (FromCBOR (..), ToCBOR (..))
+import Cardano.HeapWords (HeapWords)
 import Cardano.Ledger.Compactible
-import Cardano.Prelude (HeapWords)
 import Control.DeepSeq (NFData)
 import Data.Aeson (FromJSON, ToJSON)
 import Data.Group (Abelian, Group (..))
diff --git a/libs/cardano-ledger-core/src/Cardano/Ledger/SafeHash.hs b/libs/cardano-ledger-core/src/Cardano/Ledger/SafeHash.hs
index 7221d2cb3a0..2aaaba31b2f 100644
--- a/libs/cardano-ledger-core/src/Cardano/Ledger/SafeHash.hs
+++ b/libs/cardano-ledger-core/src/Cardano/Ledger/SafeHash.hs
@@ -58,8 +58,8 @@ where
 
 import Cardano.Binary (FromCBOR (..), ToCBOR (..))
 import qualified Cardano.Crypto.Hash as Hash
+import Cardano.HeapWords (HeapWords (..))
 import qualified Cardano.Ledger.Crypto as CC
-import Cardano.Prelude (HeapWords (..))
 import Control.DeepSeq (NFData)
 import Data.ByteString (ByteString)
 import Data.ByteString.Short (ShortByteString, fromShort)
diff --git a/libs/cardano-ledger-core/src/Cardano/Ledger/TxIn.hs b/libs/cardano-ledger-core/src/Cardano/Ledger/TxIn.hs
index dde150b064d..430f77e183a 100644
--- a/libs/cardano-ledger-core/src/Cardano/Ledger/TxIn.hs
+++ b/libs/cardano-ledger-core/src/Cardano/Ledger/TxIn.hs
@@ -27,6 +27,8 @@ import Cardano.Binary (FromCBOR (fromCBOR), ToCBOR (..), encodeListLen)
 import Cardano.Ledger.BaseTypes (TxIx (..), mkTxIxPartial)
 import qualified Cardano.Ledger.Crypto as CC
 import Cardano.Ledger.Hashes (EraIndependentTxBody)
+import Cardano.HeapWords (HeapWords (..))
+import qualified Cardano.HeapWords as HW
 import Cardano.Ledger.SafeHash (SafeHash)
 import Cardano.Ledger.Serialization (decodeRecordNamed)
 import Cardano.Prelude (HeapWords (..))