diff --git a/cabal.project b/cabal.project
index 671bd2adbf7..0244fb97fac 100644
--- a/cabal.project
+++ b/cabal.project
@@ -120,25 +120,25 @@ source-repository-package
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/cardano-ledger
-  tag: e8475e33772e7408e83ff22e4406673ea73f93fd
+  tag: 6d533b72d4a91b756cd8ffe164928d5f5eebcfa0
   subdir: cardano-ledger
 
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/cardano-ledger
-  tag: e8475e33772e7408e83ff22e4406673ea73f93fd
+  tag: 6d533b72d4a91b756cd8ffe164928d5f5eebcfa0
   subdir: crypto
 
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/cardano-ledger
-  tag: e8475e33772e7408e83ff22e4406673ea73f93fd
+  tag: 6d533b72d4a91b756cd8ffe164928d5f5eebcfa0
   subdir: cardano-ledger/test
 
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/cardano-ledger
-  tag: e8475e33772e7408e83ff22e4406673ea73f93fd
+  tag: 6d533b72d4a91b756cd8ffe164928d5f5eebcfa0
   subdir: crypto/test
 
 -- version number matching the one specified in the stack resolver file
diff --git a/nix/.stack.nix/cardano-crypto-test.nix b/nix/.stack.nix/cardano-crypto-test.nix
index bcb18219bc9..43d7c13db01 100644
--- a/nix/.stack.nix/cardano-crypto-test.nix
+++ b/nix/.stack.nix/cardano-crypto-test.nix
@@ -34,8 +34,8 @@
     } // {
     src = (pkgs.lib).mkDefault (pkgs.fetchgit {
       url = "https://github.com/input-output-hk/cardano-ledger";
-      rev = "e8475e33772e7408e83ff22e4406673ea73f93fd";
-      sha256 = "1pb6fr91g4nmgds71av767hzwfmmkpmp9ldvdkr14v1hv7cqg4kx";
+      rev = "6d533b72d4a91b756cd8ffe164928d5f5eebcfa0";
+      sha256 = "08jbmlq5jj36jkn2iw9znl7jkgnjgq37i70asmp62igqyjhis8q6";
       });
     postUnpack = "sourceRoot+=/crypto/test; echo source root reset to \$sourceRoot";
     }
\ No newline at end of file
diff --git a/nix/.stack.nix/cardano-crypto-wrapper.nix b/nix/.stack.nix/cardano-crypto-wrapper.nix
index 5511ef3faa5..830fc9d1261 100644
--- a/nix/.stack.nix/cardano-crypto-wrapper.nix
+++ b/nix/.stack.nix/cardano-crypto-wrapper.nix
@@ -59,8 +59,8 @@
     } // {
     src = (pkgs.lib).mkDefault (pkgs.fetchgit {
       url = "https://github.com/input-output-hk/cardano-ledger";
-      rev = "e8475e33772e7408e83ff22e4406673ea73f93fd";
-      sha256 = "1pb6fr91g4nmgds71av767hzwfmmkpmp9ldvdkr14v1hv7cqg4kx";
+      rev = "6d533b72d4a91b756cd8ffe164928d5f5eebcfa0";
+      sha256 = "08jbmlq5jj36jkn2iw9znl7jkgnjgq37i70asmp62igqyjhis8q6";
       });
     postUnpack = "sourceRoot+=/crypto; echo source root reset to \$sourceRoot";
     }
\ No newline at end of file
diff --git a/nix/.stack.nix/cardano-ledger-test.nix b/nix/.stack.nix/cardano-ledger-test.nix
index 66717496def..c681d2e6e07 100644
--- a/nix/.stack.nix/cardano-ledger-test.nix
+++ b/nix/.stack.nix/cardano-ledger-test.nix
@@ -55,8 +55,8 @@
     } // {
     src = (pkgs.lib).mkDefault (pkgs.fetchgit {
       url = "https://github.com/input-output-hk/cardano-ledger";
-      rev = "e8475e33772e7408e83ff22e4406673ea73f93fd";
-      sha256 = "1pb6fr91g4nmgds71av767hzwfmmkpmp9ldvdkr14v1hv7cqg4kx";
+      rev = "6d533b72d4a91b756cd8ffe164928d5f5eebcfa0";
+      sha256 = "08jbmlq5jj36jkn2iw9znl7jkgnjgq37i70asmp62igqyjhis8q6";
       });
     postUnpack = "sourceRoot+=/cardano-ledger/test; echo source root reset to \$sourceRoot";
     }
\ No newline at end of file
diff --git a/nix/.stack.nix/cardano-ledger.nix b/nix/.stack.nix/cardano-ledger.nix
index 3ce3a8405c4..c7b5e1873b9 100644
--- a/nix/.stack.nix/cardano-ledger.nix
+++ b/nix/.stack.nix/cardano-ledger.nix
@@ -118,8 +118,8 @@
     } // {
     src = (pkgs.lib).mkDefault (pkgs.fetchgit {
       url = "https://github.com/input-output-hk/cardano-ledger";
-      rev = "e8475e33772e7408e83ff22e4406673ea73f93fd";
-      sha256 = "1pb6fr91g4nmgds71av767hzwfmmkpmp9ldvdkr14v1hv7cqg4kx";
+      rev = "6d533b72d4a91b756cd8ffe164928d5f5eebcfa0";
+      sha256 = "08jbmlq5jj36jkn2iw9znl7jkgnjgq37i70asmp62igqyjhis8q6";
       });
     postUnpack = "sourceRoot+=/cardano-ledger; echo source root reset to \$sourceRoot";
     }
\ No newline at end of file
diff --git a/nix/.stack.nix/typed-protocols-examples.nix b/nix/.stack.nix/typed-protocols-examples.nix
index 57064b8d55a..a1c886c6f3f 100644
--- a/nix/.stack.nix/typed-protocols-examples.nix
+++ b/nix/.stack.nix/typed-protocols-examples.nix
@@ -43,4 +43,4 @@
           };
         };
       };
-    } // rec { src = (pkgs.lib).mkDefault ../../././typed-protocols-examples; }
+    } // rec { src = (pkgs.lib).mkDefault ../../././typed-protocols-examples; }
\ No newline at end of file
diff --git a/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/Mempool.hs b/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/Mempool.hs
index c5a034f3415..548eaee80a2 100644
--- a/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/Mempool.hs
+++ b/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/Mempool.hs
@@ -64,6 +64,7 @@ import qualified Cardano.Chain.ValidationMode as CC
 
 import           Ouroboros.Consensus.Ledger.Abstract
 import           Ouroboros.Consensus.Ledger.Byron.Block
+import           Ouroboros.Consensus.Ledger.Byron.Conversions (toByronSlotNo)
 import           Ouroboros.Consensus.Ledger.Byron.Ledger
 import           Ouroboros.Consensus.Ledger.Byron.Orphans ()
 import           Ouroboros.Consensus.Mempool.API
@@ -193,6 +194,7 @@ applyByronGenTx validationMode cfg genTx (TickedLedgerState slot st) =
       CC.applyMempoolPayload
         validationMode
         (unByronLedgerConfig cfg)
+        (toByronSlotNo slot)
         (toMempoolPayload genTx)
         (byronLedgerState st)
 
diff --git a/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/PBFT.hs b/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/PBFT.hs
index 78946ddfea1..322c26d5c14 100644
--- a/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/PBFT.hs
+++ b/ouroboros-consensus/src/Ouroboros/Consensus/Ledger/Byron/PBFT.hs
@@ -21,7 +21,6 @@ import           Cardano.Binary (Annotated)
 import           Cardano.Crypto.DSIGN
 
 import qualified Cardano.Chain.Block as CC
-import qualified Cardano.Chain.Byron.API as CC
 import qualified Cardano.Chain.Delegation as Delegation
 
 import           Ouroboros.Network.Block (HasHeader (..))
diff --git a/ouroboros-consensus/src/Ouroboros/Consensus/Node/Run/Byron.hs b/ouroboros-consensus/src/Ouroboros/Consensus/Node/Run/Byron.hs
index 5b325c0f1de..e46f7860180 100644
--- a/ouroboros-consensus/src/Ouroboros/Consensus/Node/Run/Byron.hs
+++ b/ouroboros-consensus/src/Ouroboros/Consensus/Node/Run/Byron.hs
@@ -42,8 +42,8 @@ instance RunNode ByronBlock where
   nodeBlockMatchesHeader    = verifyBlockMatchesHeader
   nodeBlockFetchSize        = const 2000 -- TODO #593
   nodeIsEBB                 = \hdr -> case byronHeaderRaw hdr of
-    API.ABOBBlockHdr _       -> Nothing
-    API.ABOBBoundaryHdr bhdr -> Just
+    Cardano.Block.ABOBBlockHdr _       -> Nothing
+    Cardano.Block.ABOBBoundaryHdr bhdr -> Just
                               . EpochNo
                               . Cardano.Block.boundaryEpoch
                               $ bhdr
diff --git a/ouroboros-consensus/test-consensus/Test/Consensus/Ledger/Byron.hs b/ouroboros-consensus/test-consensus/Test/Consensus/Ledger/Byron.hs
index 3bf826716f1..c4c7fcb0460 100644
--- a/ouroboros-consensus/test-consensus/Test/Consensus/Ledger/Byron.hs
+++ b/ouroboros-consensus/test-consensus/Test/Consensus/Ledger/Byron.hs
@@ -24,7 +24,7 @@ import qualified Data.ByteString.Lazy.Char8 as Lazy8
 import qualified Data.Sequence.Strict as Seq
 
 import           Cardano.Binary (fromCBOR, toCBOR)
-import           Cardano.Chain.Block (ABlockOrBoundary (..))
+import           Cardano.Chain.Block (ABlockOrBoundary (..), ABlockOrBoundaryHdr(..))
 import qualified Cardano.Chain.Block as CC.Block
 import qualified Cardano.Chain.Byron.API as API
 import           Cardano.Chain.Common (KeyHash)
@@ -455,14 +455,14 @@ instance Arbitrary (Header ByronBlock) where
     where
       genHeader :: Gen (Header ByronBlock)
       genHeader =
-        mkByronHeader epochSlots . API.ABOBBlockHdr .
+        mkByronHeader epochSlots . ABOBBlockHdr .
         API.reAnnotateUsing
           (CC.Block.toCBORHeader epochSlots)
           (CC.Block.fromCBORAHeader epochSlots) <$>
         hedgehog (CC.genHeader protocolMagicId epochSlots)
       genBoundaryHeader :: Gen (Header ByronBlock)
       genBoundaryHeader =
-        mkByronHeader epochSlots . API.ABOBBoundaryHdr .
+        mkByronHeader epochSlots . ABOBBoundaryHdr .
         API.reAnnotateUsing
           (CC.Block.toCBORABoundaryHeader protocolMagicId)
           CC.Block.fromCBORABoundaryHeader <$>
diff --git a/stack.yaml b/stack.yaml
index c9c2b7542f8..8ee06abf208 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -51,7 +51,7 @@ extra-deps:
   - gray-code-0.3.1
 
   - git: https://github.com/input-output-hk/cardano-ledger
-    commit: e8475e33772e7408e83ff22e4406673ea73f93fd
+    commit: 6d533b72d4a91b756cd8ffe164928d5f5eebcfa0
     subdirs:
       - cardano-ledger
       - cardano-ledger/test