diff --git a/beacon_chain/spec/mev/bellatrix_mev.nim b/beacon_chain/spec/mev/bellatrix_mev.nim
index b57bda273..fde610e76 100644
--- a/beacon_chain/spec/mev/bellatrix_mev.nim
+++ b/beacon_chain/spec/mev/bellatrix_mev.nim
@@ -5,14 +5,33 @@
 #   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import "."/[altair, bellatrix]
+import ".."/datatypes/[altair, bellatrix]
 
 {.push raises: [Defect].}
 
 type
-  # https://github.com/flashbots/mev-boost/blob/thegostep/docs/docs/milestone-1.md#blindedbeaconblockbody
-  # This is forked from bellatrix.BeaconBlockBody with execution_payload
-  # replaced with execution_payload_header
+  # https://github.com/lightclient/builder-specs/blob/198f9e15c3764b7c3b0fbd9ec8bef3391ceeab61/specs/README.md#validatorregistrationv1
+  ValidatorRegistrationV1 = object
+    feeRecipient*: ExecutionAddress
+    gasLimit*: uint64
+    timestamp*: uint64
+    pubkey*: ValidatorPubKey
+
+  # https://github.com/lightclient/builder-specs/blob/198f9e15c3764b7c3b0fbd9ec8bef3391ceeab61/specs/README.md#builderbidv1
+  BuilderBidV1 = object
+    header*: ExecutionPayloadHeader
+    value*: Eth2Digest   # uint256
+    pubkey*: ValidatorPubKey
+
+  # https://github.com/lightclient/builder-specs/blob/198f9e15c3764b7c3b0fbd9ec8bef3391ceeab61/specs/README.md#blindedbeaconblock
+  BlindedBeaconBlock = object
+    slot*: Slot
+    proposer_index*: uint64
+    parent_root*: Eth2Digest
+    state_root*: Eth2Digest
+    body*: BlindedBeaconBlockBody
+
+  # https://github.com/lightclient/builder-specs/blob/198f9e15c3764b7c3b0fbd9ec8bef3391ceeab61/specs/README.md#blindedbeaconblockbody
   BlindedBeaconBlockBody = object
     randao_reveal*: ValidatorSig
     eth1_data*: Eth1Data
@@ -25,16 +44,7 @@ type
     sync_aggregate*: SyncAggregate
     execution_payload_header*: ExecutionPayloadHeader
 
-  # https://github.com/flashbots/mev-boost/blob/thegostep/docs/docs/milestone-1.md#blindedbeaconblock
-  # This is forked from bellatrix.BeaconBlock with body replaced with
-  # BlindedBeaconBlockBody
-  BlindedBeaconBlock = object
-    slot*: Slot
-    proposer_index*: uint64
-    parent_root*: Eth2Digest
-    state_root*: Eth2Digest
-    body*: BlindedBeaconBlockBody
-
+  # TODO current spec PR doesn't have this yet
   # https://github.com/flashbots/mev-boost/blob/thegostep/docs/docs/milestone-1.md#signedblindedbeaconblock
   SignedBlindedBeaconBlock = object
     message*: BlindedBeaconBlock