diff --git a/arbos/arbostypes/incomingmessage.go b/arbos/arbostypes/incomingmessage.go
index 58186b7108..e9a5466d46 100644
--- a/arbos/arbostypes/incomingmessage.go
+++ b/arbos/arbostypes/incomingmessage.go
@@ -158,7 +158,7 @@ func (msg *L1IncomingMessage) FillInBatchGasCost(batchFetcher FallibleBatchFetch
 	if batchFetcher == nil || msg.Header.Kind != L1MessageType_BatchPostingReport || msg.BatchGasCost != nil {
 		return nil
 	}
-	_, _, batchHash, batchNum, _, err := ParseBatchPostingReportMessageFields(bytes.NewReader(msg.L2msg))
+	_, _, batchHash, batchNum, _, _, err := ParseBatchPostingReportMessageFields(bytes.NewReader(msg.L2msg))
 	if err != nil {
 		return fmt.Errorf("failed to parse batch posting report: %w", err)
 	}
@@ -290,30 +290,39 @@ func (msg *L1IncomingMessage) ParseInitMessage() (*ParsedInitMessage, error) {
 	return nil, fmt.Errorf("invalid init message data %v", string(msg.L2msg))
 }
 
-func ParseBatchPostingReportMessageFields(rd io.Reader) (*big.Int, common.Address, common.Hash, uint64, *big.Int, error) {
+func ParseBatchPostingReportMessageFields(rd io.Reader) (*big.Int, common.Address, common.Hash, uint64, *big.Int, uint64, error) {
 	batchTimestamp, err := util.HashFromReader(rd)
 	if err != nil {
-		return nil, common.Address{}, common.Hash{}, 0, nil, err
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
 	}
 	batchPosterAddr, err := util.AddressFromReader(rd)
 	if err != nil {
-		return nil, common.Address{}, common.Hash{}, 0, nil, err
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
 	}
 	dataHash, err := util.HashFromReader(rd)
 	if err != nil {
-		return nil, common.Address{}, common.Hash{}, 0, nil, err
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
 	}
 	batchNum, err := util.HashFromReader(rd)
 	if err != nil {
-		return nil, common.Address{}, common.Hash{}, 0, nil, err
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
 	}
 	l1BaseFee, err := util.HashFromReader(rd)
 	if err != nil {
-		return nil, common.Address{}, common.Hash{}, 0, nil, err
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
+	}
+	extraGas, err := util.Uint64FromReader(rd)
+	if errors.Is(err, io.EOF) {
+		// This field isn't always present
+		extraGas = 0
+		err = nil
+	}
+	if err != nil {
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, err
 	}
 	batchNumBig := batchNum.Big()
 	if !batchNumBig.IsUint64() {
-		return nil, common.Address{}, common.Hash{}, 0, nil, fmt.Errorf("batch number %v is not a uint64", batchNumBig)
+		return nil, common.Address{}, common.Hash{}, 0, nil, 0, fmt.Errorf("batch number %v is not a uint64", batchNumBig)
 	}
-	return batchTimestamp.Big(), batchPosterAddr, dataHash, batchNumBig.Uint64(), l1BaseFee.Big(), nil
+	return batchTimestamp.Big(), batchPosterAddr, dataHash, batchNumBig.Uint64(), l1BaseFee.Big(), extraGas, nil
 }
diff --git a/arbos/parse_l2.go b/arbos/parse_l2.go
index 5e8a9a5fc4..88018fdfcf 100644
--- a/arbos/parse_l2.go
+++ b/arbos/parse_l2.go
@@ -15,6 +15,7 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/offchainlabs/nitro/arbos/arbostypes"
 	"github.com/offchainlabs/nitro/arbos/util"
+	"github.com/offchainlabs/nitro/util/arbmath"
 )
 
 type InfallibleBatchFetcher func(batchNum uint64, batchHash common.Hash) []byte
@@ -370,7 +371,7 @@ func parseSubmitRetryableMessage(rd io.Reader, header *arbostypes.L1IncomingMess
 }
 
 func parseBatchPostingReportMessage(rd io.Reader, chainId *big.Int, msgBatchGasCost *uint64, batchFetcher InfallibleBatchFetcher) (*types.Transaction, error) {
-	batchTimestamp, batchPosterAddr, batchHash, batchNum, l1BaseFee, err := arbostypes.ParseBatchPostingReportMessageFields(rd)
+	batchTimestamp, batchPosterAddr, batchHash, batchNum, l1BaseFee, extraGas, err := arbostypes.ParseBatchPostingReportMessageFields(rd)
 	if err != nil {
 		return nil, err
 	}
@@ -381,6 +382,7 @@ func parseBatchPostingReportMessage(rd io.Reader, chainId *big.Int, msgBatchGasC
 		batchData := batchFetcher(batchNum, batchHash)
 		batchDataGas = arbostypes.ComputeBatchGasCost(batchData)
 	}
+	batchDataGas = arbmath.SaturatingUAdd(batchDataGas, extraGas)
 
 	data, err := util.PackInternalTxDataBatchPostingReport(
 		batchTimestamp, batchPosterAddr, batchNum, batchDataGas, l1BaseFee,
diff --git a/contracts b/contracts
index 51cd559016..1b10711dc5 160000
--- a/contracts
+++ b/contracts
@@ -1 +1 @@
-Subproject commit 51cd55901676ec998c5260f779c385b77855d817
+Subproject commit 1b10711dc5f2eeefebc8c9f07d5c5f580534f703