diff --git a/op-node/rollup/derive/attributes.go b/op-node/rollup/derive/attributes.go
index 2dc32e09c..d245643f4 100644
--- a/op-node/rollup/derive/attributes.go
+++ b/op-node/rollup/derive/attributes.go
@@ -126,9 +126,9 @@ func (ba *FetchingAttributesBuilder) PreparePayloadAttributes(ctx context.Contex
 
 	// Sanity check the L1 origin was correctly selected to maintain the time invariant between L1 and L2
 	nextL2MilliTime := l2Parent.MillisecondTimestamp() + ba.rollupCfg.BlockTime
-	if nextL2MilliTime < l1Info.MilliTime() {
+	if nextL2MilliTime < l1Info.MillTimestamp() {
 		return nil, NewResetError(fmt.Errorf("cannot build L2 block on top %s for time %d before L1 origin %s at time %d",
-			l2Parent, nextL2MilliTime, eth.ToBlockID(l1Info), l1Info.MilliTime()))
+			l2Parent, nextL2MilliTime, eth.ToBlockID(l1Info), l1Info.MillTimestamp()))
 	}
 
 	var upgradeTxs []hexutil.Bytes
diff --git a/op-node/service.go b/op-node/service.go
index fa54cf0bc..e36001fe5 100644
--- a/op-node/service.go
+++ b/op-node/service.go
@@ -27,6 +27,12 @@ import (
 	opflags "github.com/ethereum-optimism/optimism/op-service/flags"
 )
 
+const (
+	MinBlockTimeSeconds = 1
+	MaxBlockTimeSeconds = 3
+	MaxBlockTimeMs      = 750
+)
+
 // NewConfig creates a Config from the provided flags or environment variables.
 func NewConfig(ctx *cli.Context, log log.Logger) (*node.Config, error) {
 	if err := flags.CheckRequired(ctx); err != nil {
@@ -44,11 +50,11 @@ func NewConfig(ctx *cli.Context, log log.Logger) (*node.Config, error) {
 	}
 
 	{
-		if rollupConfig.BlockTime >= 1 && rollupConfig.BlockTime <= 3 {
+		if rollupConfig.BlockTime >= MinBlockTimeSeconds && rollupConfig.BlockTime <= MaxBlockTimeSeconds {
 			// Convert legacy second-level timestamp to millisecond timestamp,
 			// This is a compatibility behavior.
 			rollupConfig.BlockTime = rollupConfig.BlockTime * 1000
-		} else if rollupConfig.BlockTime%50 != 0 && rollupConfig.BlockTime > 750 {
+		} else if rollupConfig.BlockTime%50 != 0 && rollupConfig.BlockTime > MaxBlockTimeMs {
 			return nil, fmt.Errorf("block time is invalid, block_time: %v", rollupConfig.BlockTime)
 		}
 		// rollupConfig.BlockTime is millisecond block interval
diff --git a/op-service/eth/block_info.go b/op-service/eth/block_info.go
index f712beeed..5701d757b 100644
--- a/op-service/eth/block_info.go
+++ b/op-service/eth/block_info.go
@@ -7,6 +7,7 @@ import (
 	"github.com/ethereum/go-ethereum/consensus/misc/eip4844"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/holiman/uint256"
 )
 
 type BlockInfo interface {
@@ -16,7 +17,8 @@ type BlockInfo interface {
 	Root() common.Hash // state-root
 	NumberU64() uint64
 	Time() uint64
-	MilliTime() uint64
+	MillTimestamp() uint64
+	MillSeconds() uint64
 	// MixDigest field, reused for randomness after The Merge (Bellatrix hardfork)
 	MixDigest() common.Hash
 	BaseFee() *big.Int
@@ -39,6 +41,7 @@ func InfoToL1BlockRef(info BlockInfo) L1BlockRef {
 		Number:     info.NumberU64(),
 		ParentHash: info.ParentHash(),
 		Time:       info.Time(),
+		mTime:      info.MillSeconds(),
 	}
 }
 
@@ -73,9 +76,15 @@ func (b blockInfo) ParentBeaconRoot() *common.Hash {
 	return b.Block.BeaconRoot()
 }
 
-func (b blockInfo) MilliTime() uint64 {
-	// TODO: adapt L1 timestamp
-	return b.Block.Time() * 1000
+func (b blockInfo) MillTimestamp() uint64 {
+	return b.Block.Time()*1000 + b.MillSeconds()
+}
+
+func (b blockInfo) MillSeconds() uint64 {
+	if b.MixDigest() == (common.Hash{}) {
+		return 0
+	}
+	return uint256.NewInt(0).SetBytes32(b.MixDigest().Bytes()).Uint64()
 }
 
 func BlockToInfo(b *types.Block) BlockInfo {
@@ -108,9 +117,15 @@ func (h headerBlockInfo) Time() uint64 {
 	return h.Header.Time
 }
 
-func (h headerBlockInfo) MilliTime() uint64 {
-	// TODO: adapt L1 timestamp
-	return h.Header.Time * 1000
+func (h headerBlockInfo) MillTimestamp() uint64 {
+	return h.Header.Time*1000 + h.MillSeconds()
+}
+
+func (h headerBlockInfo) MillSeconds() uint64 {
+	if h.MixDigest() == (common.Hash{}) {
+		return 0
+	}
+	return uint256.NewInt(0).SetBytes32(h.MixDigest().Bytes()).Uint64()
 }
 
 func (h headerBlockInfo) MixDigest() common.Hash {
diff --git a/op-service/eth/heads.go b/op-service/eth/heads.go
index db837cbbe..b419c268b 100644
--- a/op-service/eth/heads.go
+++ b/op-service/eth/heads.go
@@ -5,9 +5,11 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
+	"github.com/holiman/uint256"
 )
 
 // HeadSignalFn is used as callback function to accept head-signals
@@ -43,11 +45,18 @@ func WatchHeadChanges(ctx context.Context, src NewHeadSource, fn HeadSignalFn) (
 		for {
 			select {
 			case header := <-headChanges:
+				var mTime uint64
+				if header.MixDigest == (common.Hash{}) {
+					mTime = header.Time
+				} else {
+					mTime = uint256.NewInt(0).SetBytes32(header.MixDigest[:]).Uint64()
+				}
 				fn(eventsCtx, L1BlockRef{
 					Hash:       header.Hash(),
 					Number:     header.Number.Uint64(),
 					ParentHash: header.ParentHash,
-					Time:       header.Time,
+					Time:       mTime,
+					mTime:      mTime,
 				})
 			case <-eventsCtx.Done():
 				return nil
diff --git a/op-service/eth/id.go b/op-service/eth/id.go
index e221508e3..7aa20cf45 100644
--- a/op-service/eth/id.go
+++ b/op-service/eth/id.go
@@ -59,12 +59,11 @@ type L1BlockRef struct {
 	Number     uint64      `json:"number"`
 	ParentHash common.Hash `json:"parentHash"`
 	Time       uint64      `json:"timestamp"`
-	// TODO:
+	mTime      uint64      `json:"timestamp"` // millisecond representation
 }
 
 func (id L1BlockRef) MilliTimestamp() uint64 {
-	// TODO: adapt L1
-	return id.Time * 1000
+	return id.Time*1000 + id.mTime
 }
 
 func (id L1BlockRef) String() string {
diff --git a/op-service/sources/types.go b/op-service/sources/types.go
index b57beb7db..05237e8e0 100644
--- a/op-service/sources/types.go
+++ b/op-service/sources/types.go
@@ -63,9 +63,15 @@ func (h headerInfo) Time() uint64 {
 	return h.Header.Time
 }
 
-func (h headerInfo) MilliTime() uint64 {
-	// TODO: adapt L1 timestamp
-	return h.Header.Time * 1000
+func (h headerInfo) MillTimestamp() uint64 {
+	return h.Header.Time*1000 + h.MillSeconds()
+}
+
+func (h headerInfo) MillSeconds() uint64 {
+	if h.MixDigest() == (common.Hash{}) {
+		return 0
+	}
+	return uint256.NewInt(0).SetBytes32(h.MixDigest().Bytes()).Uint64()
 }
 
 func (h headerInfo) MixDigest() common.Hash {
diff --git a/op-service/testutils/l1info.go b/op-service/testutils/l1info.go
index dcc45604d..c5d0cc1b3 100644
--- a/op-service/testutils/l1info.go
+++ b/op-service/testutils/l1info.go
@@ -21,6 +21,7 @@ type MockBlockInfo struct {
 	InfoRoot        common.Hash
 	InfoNum         uint64
 	InfoTime        uint64
+	InfoMTime       uint64
 	InfoMixDigest   [32]byte
 	InfoBaseFee     *big.Int
 	InfoBlobBaseFee *big.Int
@@ -56,10 +57,14 @@ func (l *MockBlockInfo) Time() uint64 {
 	return l.InfoTime
 }
 
-func (l *MockBlockInfo) MilliTime() uint64 {
+func (l *MockBlockInfo) MillTimestamp() uint64 {
 	return l.InfoTime * 1000
 }
 
+func (l *MockBlockInfo) MillSeconds() uint64 {
+	return l.InfoMTime
+}
+
 func (l *MockBlockInfo) MixDigest() common.Hash {
 	return l.InfoMixDigest
 }