diff --git a/pkg/client/chain_client_test.go b/pkg/client/chain_client_test.go
index 47ce847146..8be608619a 100644
--- a/pkg/client/chain_client_test.go
+++ b/pkg/client/chain_client_test.go
@@ -504,7 +504,8 @@ type sendTxService struct {
 	sentCount atomic.Int32
 }
 
-func (x *sendTxService) ChainID(ctx context.Context) (*hexutil.Big, error) {
+//nolint:revive // ChainId must match JSON-RPC method name eth_chainId, not ChainID
+func (x *sendTxService) ChainId(ctx context.Context) (*hexutil.Big, error) {
 	return (*hexutil.Big)(x.chainID), nil
 }
 
@@ -846,7 +847,7 @@ func TestEthClient_ErroringClient(t *testing.T) {
 	require.Equal(t, multinode.ErrNodeError, err)
 
 	id := erroringClient.ConfiguredChainID()
-	require.Equal(t, id, big.NewInt(0))
+	require.Equal(t, id, big.NewInt(evmtypes.NullClientChainID))
 
 	_, err = erroringClient.CodeAt(ctx, common.Address{}, nil)
 	require.Equal(t, multinode.ErrNodeError, err)
diff --git a/pkg/client/clienttest/clienttest.go b/pkg/client/clienttest/clienttest.go
index a3928bee98..f31d2447f7 100644
--- a/pkg/client/clienttest/clienttest.go
+++ b/pkg/client/clienttest/clienttest.go
@@ -8,11 +8,13 @@ import (
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/stretchr/testify/mock"
+
+	"github.com/smartcontractkit/chainlink-evm/pkg/types"
 )
 
 func NewClientWithDefaultChainID(t testing.TB) *Client {
 	c := NewClient(t)
-	c.On("ConfiguredChainID").Return(big.NewInt(0)).Maybe()
+	c.On("ConfiguredChainID").Return(big.NewInt(types.NullClientChainID)).Maybe()
 	return c
 }
 
diff --git a/pkg/client/null_client.go b/pkg/client/null_client.go
index e2fe66610d..06cd56db9a 100644
--- a/pkg/client/null_client.go
+++ b/pkg/client/null_client.go
@@ -30,7 +30,7 @@ func NewNullClient(cid *big.Int, lggr logger.Logger) *NullClient {
 
 // NullClientChainID the ChainID that nullclient will return
 // 0 is never used as a real chain ID so makes sense as a dummy value here
-const NullClientChainID = 0
+const NullClientChainID = evmtypes.NullClientChainID
 
 //
 // Client methods
diff --git a/pkg/config/configtest/configtest.go b/pkg/config/configtest/configtest.go
index fa74f5bf11..f55f40c7c5 100644
--- a/pkg/config/configtest/configtest.go
+++ b/pkg/config/configtest/configtest.go
@@ -5,11 +5,12 @@ import (
 
 	"github.com/smartcontractkit/chainlink-evm/pkg/config"
 	"github.com/smartcontractkit/chainlink-evm/pkg/config/toml"
+	"github.com/smartcontractkit/chainlink-evm/pkg/types"
 	"github.com/smartcontractkit/chainlink-evm/pkg/utils/big"
 )
 
 func NewChainScopedConfig(t testing.TB, overrideFn func(c *toml.EVMConfig)) *config.ChainScoped {
-	chainID := big.NewI(0)
+	chainID := big.NewI(types.NullClientChainID)
 	evmCfg := &toml.EVMConfig{
 		ChainID: chainID,
 		Chain:   toml.Defaults(chainID),
diff --git a/pkg/gas/fee_history_estimator_test.go b/pkg/gas/fee_history_estimator_test.go
index 72235435cb..7bcd1b98fd 100644
--- a/pkg/gas/fee_history_estimator_test.go
+++ b/pkg/gas/fee_history_estimator_test.go
@@ -16,6 +16,7 @@ import (
 	"github.com/smartcontractkit/chainlink-evm/pkg/assets"
 	"github.com/smartcontractkit/chainlink-evm/pkg/gas"
 	"github.com/smartcontractkit/chainlink-evm/pkg/gas/mocks"
+	"github.com/smartcontractkit/chainlink-evm/pkg/testutils"
 	"github.com/smartcontractkit/chainlink-framework/chains/fees"
 )
 
@@ -23,7 +24,7 @@ func TestFeeHistoryEstimatorLifecycle(t *testing.T) {
 	t.Parallel()
 	var gasLimit uint64 = 21000
 	maxPrice := assets.NewWeiI(100)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 
 	t.Run("fails if you fetch gas price before the estimator starts", func(t *testing.T) {
 		cfg := gas.FeeHistoryEstimatorConfig{
@@ -78,7 +79,7 @@ func TestFeeHistoryEstimatorGetLegacyGas(t *testing.T) {
 
 	var gasLimit uint64 = 21000
 	maxPrice := assets.NewWeiI(100)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 
 	t.Run("fetches a new gas price when first called", func(t *testing.T) {
 		client := mocks.NewFeeHistoryEstimatorClient(t)
@@ -125,7 +126,7 @@ func TestFeeHistoryEstimatorBumpLegacyGas(t *testing.T) {
 
 	var gasLimit uint64 = 21000
 	maxPrice := assets.NewWeiI(100)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 
 	t.Run("bumps a previous attempt by BumpPercent", func(t *testing.T) {
 		client := mocks.NewFeeHistoryEstimatorClient(t)
@@ -216,7 +217,7 @@ func TestFeeHistoryEstimatorGetDynamicFee(t *testing.T) {
 	t.Parallel()
 
 	maxPrice := assets.NewWeiI(100)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 
 	t.Run("fetches a new dynamic fee when first called", func(t *testing.T) {
 		client := mocks.NewFeeHistoryEstimatorClient(t)
@@ -287,7 +288,7 @@ func TestFeeHistoryEstimatorBumpDynamicFee(t *testing.T) {
 	t.Parallel()
 
 	globalMaxPrice := assets.NewWeiI(100)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 
 	t.Run("bumps a previous attempt by BumpPercent", func(t *testing.T) {
 		client := mocks.NewFeeHistoryEstimatorClient(t)
diff --git a/pkg/heads/saver_test.go b/pkg/heads/saver_test.go
index ff83910b06..a4633f566d 100644
--- a/pkg/heads/saver_test.go
+++ b/pkg/heads/saver_test.go
@@ -12,11 +12,11 @@ import (
 	"github.com/smartcontractkit/chainlink-common/pkg/utils/tests"
 
 	evmheads "github.com/smartcontractkit/chainlink-evm/pkg/heads"
+	ubig "github.com/smartcontractkit/chainlink-evm/pkg/utils/big"
 
 	"github.com/smartcontractkit/chainlink-evm/pkg/testutils"
 	evmtypes "github.com/smartcontractkit/chainlink-evm/pkg/types"
 	"github.com/smartcontractkit/chainlink-evm/pkg/utils"
-	ubig "github.com/smartcontractkit/chainlink-evm/pkg/utils/big"
 )
 
 type trackerConfig struct {
@@ -121,7 +121,7 @@ func TestHeadSaver_Load(t *testing.T) {
 	//           H2Uncle
 	//
 	newHead := func(num int, parent common.Hash) *evmtypes.Head {
-		h := evmtypes.NewHead(big.NewInt(int64(num)), utils.NewHash(), parent, ubig.NewI(0))
+		h := evmtypes.NewHead(big.NewInt(int64(num)), utils.NewHash(), parent, ubig.New(testutils.FixtureChainID))
 		return &h
 	}
 	h0 := newHead(0, utils.NewHash())
diff --git a/pkg/log/integration_test.go b/pkg/log/integration_test.go
index 74605acec5..5d70fc7cf7 100644
--- a/pkg/log/integration_test.go
+++ b/pkg/log/integration_test.go
@@ -1545,7 +1545,7 @@ func TestBroadcaster_BroadcastsWithZeroConfirmations(t *testing.T) {
 
 	ethClient := clienttest.NewClient(t)
 	mockEth := &clienttest.MockEth{EthClient: ethClient}
-	ethClient.On("ConfiguredChainID").Return(big.NewInt(0)).Maybe()
+	ethClient.On("ConfiguredChainID").Return(testutils.FixtureChainID).Maybe()
 	logsChCh := make(chan testutils.RawSub[types.Log])
 	ethClient.On("SubscribeFilterLogs", mock.Anything, mock.Anything, mock.Anything).
 		Return(
diff --git a/pkg/testutils/evmtypes.go b/pkg/testutils/evmtypes.go
index ecb7e8e475..3c81dfed61 100644
--- a/pkg/testutils/evmtypes.go
+++ b/pkg/testutils/evmtypes.go
@@ -19,10 +19,10 @@ import (
 	ubig "github.com/smartcontractkit/chainlink-evm/pkg/utils/big"
 )
 
-// FixtureChainID matches the chain always added by fixtures.sql
-// It is set to 0 since no real chain ever has this ID and allows a virtual
-// "test" chain ID to be used without clashes
-var FixtureChainID = big.NewInt(0)
+// FixtureChainID is set to a chainID that is unlikely to be used in production.
+// It can no longer be zero due to a breaking change in go-ethereum:
+// https://github.com/ethereum/go-ethereum/blob/master/core/types/transaction_signing.go#L193
+var FixtureChainID = big.NewInt(evmtypes.NullClientChainID)
 
 // SimulatedChainID is the chain ID for the go-ethereum simulated backend
 var SimulatedChainID = big.NewInt(1337)
diff --git a/pkg/txmgr/broadcaster_benchmark_test.go b/pkg/txmgr/broadcaster_benchmark_test.go
index c63c504d78..87a3781690 100644
--- a/pkg/txmgr/broadcaster_benchmark_test.go
+++ b/pkg/txmgr/broadcaster_benchmark_test.go
@@ -54,6 +54,7 @@ func BenchmarkEthBroadcaster_ProcessUnstartedEthTxs_Success(b *testing.B) {
 		FeeLimit:       gasLimit,
 		CreatedAt:      time.Unix(0, 0),
 		State:          txmgrcommon.TxUnstarted,
+		ChainID:        testutils.FixtureChainID,
 	}
 
 	evmcfg := configtest.NewChainScopedConfig(b, nil)
diff --git a/pkg/txmgr/broadcaster_test.go b/pkg/txmgr/broadcaster_test.go
index 67ec070535..1055793780 100644
--- a/pkg/txmgr/broadcaster_test.go
+++ b/pkg/txmgr/broadcaster_test.go
@@ -253,6 +253,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Success(t *testing.T) {
 			FeeLimit:           gasLimit,
 			BroadcastAt:        &timeNow,
 			InitialBroadcastAt: &timeNow,
+			ChainID:            testutils.FixtureChainID,
 			Error:              null.String{},
 			State:              txmgrcommon.TxUnconfirmed,
 		}
@@ -285,6 +286,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Success(t *testing.T) {
 			FeeLimit:       gasLimit,
 			CreatedAt:      time.Unix(0, 0),
 			State:          txmgrcommon.TxUnstarted,
+			ChainID:        testutils.FixtureChainID,
 		}
 		ethClient.On("SendTransactionReturnCode", mock.Anything, mock.MatchedBy(func(tx *gethTypes.Transaction) bool {
 			return tx.Nonce() == uint64(2) && tx.Value().Cmp(big.NewInt(242)) == 0
@@ -304,6 +306,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Success(t *testing.T) {
 			CreatedAt:      time.Unix(0, 1),
 			State:          txmgrcommon.TxUnstarted,
 			Meta:           &meta,
+			ChainID:        testutils.FixtureChainID,
 		}
 		ethClient.On("SendTransactionReturnCode", mock.Anything, mock.MatchedBy(func(tx *gethTypes.Transaction) bool {
 			if tx.Nonce() != uint64(0) {
@@ -327,6 +330,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Success(t *testing.T) {
 			FeeLimit:       gasLimit,
 			CreatedAt:      time.Unix(1, 0),
 			State:          txmgrcommon.TxUnstarted,
+			ChainID:        testutils.FixtureChainID,
 		}
 		ethClient.On("SendTransactionReturnCode", mock.Anything, mock.MatchedBy(func(tx *gethTypes.Transaction) bool {
 			if tx.Nonce() != uint64(1) {
@@ -786,6 +790,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_ResumingFromCrash(t *testing.T) {
 			FeeLimit:       gasLimit,
 			Error:          null.String{},
 			State:          txmgrcommon.TxInProgress,
+			ChainID:        testutils.FixtureChainID,
 		}
 
 		secondInProgress := txmgr.Tx{
@@ -797,6 +802,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_ResumingFromCrash(t *testing.T) {
 			FeeLimit:       gasLimit,
 			Error:          null.String{},
 			State:          txmgrcommon.TxInProgress,
+			ChainID:        testutils.FixtureChainID,
 		}
 
 		require.NoError(t, txStore.InsertTx(ctx, &firstInProgress))
@@ -1162,6 +1168,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Errors(t *testing.T) {
 				State:             txmgrcommon.TxUnstarted,
 				PipelineTaskRunID: uuid.NullUUID{UUID: trID, Valid: true},
 				SignalCallback:    true,
+				ChainID:           testutils.FixtureChainID,
 			}
 
 			t.Run("with erroring callback bails out", func(t *testing.T) {
@@ -1464,6 +1471,7 @@ func TestEthBroadcaster_ProcessUnstartedEthTxs_Errors(t *testing.T) {
 		Value:          value,
 		FeeLimit:       gasLimit,
 		State:          txmgrcommon.TxUnstarted,
+		ChainID:        testutils.FixtureChainID,
 	}
 	require.NoError(t, txStore.InsertTx(ctx, &etxUnfinished))
 
@@ -1874,7 +1882,7 @@ func TestEthBroadcaster_NonceTracker_InProgressTx(t *testing.T) {
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	ethClient := clienttest.NewClientWithDefaultChainID(t)
 	evmcfg := configtest.NewChainScopedConfig(t, nil)
@@ -1912,7 +1920,7 @@ func TestEthBroadcaster_HederaBroadcastValidation(t *testing.T) {
 	db := testutils.NewSqlxDB(t)
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 	evmcfg := configtest.NewChainScopedConfig(t, nil)
 	ethClient := clienttest.NewClientWithDefaultChainID(t)
 	lggr, observed := logger.TestObserved(t, zapcore.DebugLevel)
diff --git a/pkg/txmgr/confirmer_test.go b/pkg/txmgr/confirmer_test.go
index 09548afb66..727d747621 100644
--- a/pkg/txmgr/confirmer_test.go
+++ b/pkg/txmgr/confirmer_test.go
@@ -1281,7 +1281,7 @@ func TestEthConfirmer_RebroadcastWhereNecessary_TerminallyUnderpriced_ThenGoesTh
 
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
-	kst := keys.NewChainStore(memKS, big.NewInt(0))
+	kst := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	evmcfg := configtest.NewChainScopedConfig(t, func(c *toml.EVMConfig) {
 		c.GasEstimator.PriceMax = assets.GWei(500)
@@ -1547,7 +1547,7 @@ func TestEthConfirmer_ForceRebroadcast(t *testing.T) {
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
 	config := configtest.NewChainScopedConfig(t, nil)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	mustCreateUnstartedGeneratedTx(t, txStore, fromAddress, config.EVM().ChainID())
 	mustInsertInProgressEthTx(t, txStore, 0, fromAddress)
diff --git a/pkg/txmgr/evm_tx_store_test.go b/pkg/txmgr/evm_tx_store_test.go
index a489310112..c1594fd829 100644
--- a/pkg/txmgr/evm_tx_store_test.go
+++ b/pkg/txmgr/evm_tx_store_test.go
@@ -650,7 +650,7 @@ func Test_FindTxWithIdempotencyKey(t *testing.T) {
 
 	t.Run("returns nil error if no results", func(t *testing.T) {
 		idempotencyKey := "777"
-		etx, err := txStore.FindTxWithIdempotencyKey(tests.Context(t), idempotencyKey, big.NewInt(0))
+		etx, err := txStore.FindTxWithIdempotencyKey(t.Context(), idempotencyKey, testutils.FixtureChainID)
 		require.NoError(t, err)
 		assert.Nil(t, etx)
 	})
@@ -658,11 +658,11 @@ func Test_FindTxWithIdempotencyKey(t *testing.T) {
 	t.Run("returns transaction if it exists", func(t *testing.T) {
 		idempotencyKey := "777"
 		cfg.EVM().ChainID()
-		etx := mustCreateUnstartedGeneratedTx(t, txStore, fromAddress, big.NewInt(0),
+		etx := mustCreateUnstartedGeneratedTx(t, txStore, fromAddress, testutils.FixtureChainID,
 			txRequestWithIdempotencyKey(idempotencyKey))
 		require.Equal(t, idempotencyKey, *etx.IdempotencyKey)
 
-		res, err := txStore.FindTxWithIdempotencyKey(tests.Context(t), idempotencyKey, big.NewInt(0))
+		res, err := txStore.FindTxWithIdempotencyKey(t.Context(), idempotencyKey, testutils.FixtureChainID)
 		require.NoError(t, err)
 		assert.Equal(t, etx.Sequence, res.Sequence)
 		require.Equal(t, idempotencyKey, *res.IdempotencyKey)
@@ -679,7 +679,7 @@ func Test_FindReceiptWithIdempotencyKey(t *testing.T) {
 
 	idempotencyKey := "654"
 	t.Run("returns nil error if no results", func(t *testing.T) {
-		r, err := txStore.FindReceiptWithIdempotencyKey(tests.Context(t), idempotencyKey, big.NewInt(0))
+		r, err := txStore.FindReceiptWithIdempotencyKey(t.Context(), idempotencyKey, testutils.FixtureChainID)
 		require.NoError(t, err)
 		assert.Nil(t, r)
 	})
@@ -1862,6 +1862,7 @@ func TestORM_UpdateTxStatesToFinalizedUsingTxHashes(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -2060,6 +2061,7 @@ func mustInsertTerminallyStuckTxWithAttempt(t testing.TB, txStore txmgr.TestEvmT
 		BroadcastAt:        &broadcast,
 		InitialBroadcastAt: &broadcast,
 		Error:              null.StringFrom(client.TerminallyStuckMsg),
+		ChainID:            testutils.FixtureChainID,
 	}
 	require.NoError(t, txStore.InsertTx(ctx, &tx))
 	attempt := txmgrtest.NewLegacyEthTxAttempt(t, tx.ID)
diff --git a/pkg/txmgr/finalizer_benchmark_test.go b/pkg/txmgr/finalizer_benchmark_test.go
index 48e73d39d5..6874b605f4 100644
--- a/pkg/txmgr/finalizer_benchmark_test.go
+++ b/pkg/txmgr/finalizer_benchmark_test.go
@@ -66,6 +66,7 @@ func BenchmarkFinalizer(b *testing.B) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash := insertTxAndAttemptWithIdempotencyKey(b, txStore, tx, idempotencyKey)
 		// Insert receipt for finalized block num
diff --git a/pkg/txmgr/finalizer_test.go b/pkg/txmgr/finalizer_test.go
index 9b0c1a18a3..599e928f17 100644
--- a/pkg/txmgr/finalizer_test.go
+++ b/pkg/txmgr/finalizer_test.go
@@ -78,6 +78,7 @@ func TestFinalizer_MarkTxFinalized(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash := insertTxAndAttemptWithIdempotencyKey(t, txStore, tx, idempotencyKey)
 		// Insert receipt for unfinalized block num
@@ -108,6 +109,7 @@ func TestFinalizer_MarkTxFinalized(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash := insertTxAndAttemptWithIdempotencyKey(t, txStore, tx, idempotencyKey)
 		// Insert receipt for finalized block num
@@ -140,6 +142,7 @@ func TestFinalizer_MarkTxFinalized(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash := insertTxAndAttemptWithIdempotencyKey(t, txStore, tx, idempotencyKey)
 		// Insert receipt for finalized block num
@@ -170,6 +173,7 @@ func TestFinalizer_MarkTxFinalized(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash := insertTxAndAttemptWithIdempotencyKey(t, txStore, tx, idempotencyKey)
 		// Insert receipt for finalized block num
@@ -186,6 +190,7 @@ func TestFinalizer_MarkTxFinalized(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		attemptHash = insertTxAndAttemptWithIdempotencyKey(t, txStore, tx, idempotencyKey)
 		// Insert receipt for finalized block num
diff --git a/pkg/txmgr/nonce_tracker_test.go b/pkg/txmgr/nonce_tracker_test.go
index d91ee1979e..3a2b20d6fa 100644
--- a/pkg/txmgr/nonce_tracker_test.go
+++ b/pkg/txmgr/nonce_tracker_test.go
@@ -3,7 +3,6 @@ package txmgr_test
 import (
 	"errors"
 	"fmt"
-	"math/big"
 	"math/rand"
 	"testing"
 
@@ -27,7 +26,7 @@ func TestNonceTracker_LoadSequenceMap(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	txStore := txstoremock.NewEvmTxStore(t)
 
 	client := clienttest.NewClient(t)
@@ -78,7 +77,7 @@ func TestNonceTracker_syncOnChain(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	txStore := txstoremock.NewEvmTxStore(t)
 
 	client := clienttest.NewClient(t)
@@ -134,7 +133,7 @@ func TestNonceTracker_SyncSequence(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	txStore := txstoremock.NewEvmTxStore(t)
 
 	client := clienttest.NewClient(t)
@@ -181,7 +180,7 @@ func TestNonceTracker_GetNextSequence(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	txStore := txstoremock.NewEvmTxStore(t)
 
 	client := clienttest.NewClient(t)
@@ -231,7 +230,7 @@ func TestNonceTracker_GenerateNextSequence(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	txStore := txstoremock.NewEvmTxStore(t)
 
 	client := clienttest.NewClient(t)
@@ -260,7 +259,7 @@ func Test_SetNonceAfterInit(t *testing.T) {
 	t.Parallel()
 
 	ctx := tests.Context(t)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	db := testutils.NewSqlxDB(t)
 	txStore := txmgr.NewTxStore(db, logger.Test(t))
 
diff --git a/pkg/txmgr/resender_test.go b/pkg/txmgr/resender_test.go
index bc29376aaf..5d8e826700 100644
--- a/pkg/txmgr/resender_test.go
+++ b/pkg/txmgr/resender_test.go
@@ -1,7 +1,6 @@
 package txmgr_test
 
 import (
-	"math/big"
 	"testing"
 	"time"
 
@@ -41,7 +40,7 @@ func Test_EthResender_resendUnconfirmed(t *testing.T) {
 	fromAddress := memKS.MustCreate(t)
 	fromAddress2 := memKS.MustCreate(t)
 	fromAddress3 := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	txStore := txmgrtest.NewTestTxStore(t, db)
 
@@ -67,7 +66,7 @@ func Test_EthResender_resendUnconfirmed(t *testing.T) {
 		addr3TxesRawHex = append(addr3TxesRawHex, hexutil.Encode(etx.TxAttempts[0].SignedRawTx))
 	}
 
-	er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, big.NewInt(0), lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
+	er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, testutils.FixtureChainID, lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
 
 	var resentHex = make(map[string]struct{})
 	ethClient.On("BatchCallContextAll", mock.Anything, mock.MatchedBy(func(elems []rpc.BatchElem) bool {
@@ -108,13 +107,13 @@ func Test_EthResender_alertUnconfirmed(t *testing.T) {
 	ethClient := clienttest.NewClientWithDefaultChainID(t)
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	ethClient.On("IsL2").Return(false).Maybe()
 	// Set this to the smallest non-zero value possible for the attempt to be eligible for resend
 	delay := commonconfig.MustNewDuration(1 * time.Nanosecond)
 	ccfg := testutils.NewTestChainScopedConfig(t, func(c *toml.EVMConfig) {
-		c.Chain = toml.Defaults(ubig.New(big.NewInt(0)), &toml.Chain{
+		c.Chain = toml.Defaults(ubig.New(testutils.FixtureChainID), &toml.Chain{
 			Transactions: toml.Transactions{ResendAfterThreshold: delay},
 		})
 	})
@@ -122,7 +121,7 @@ func Test_EthResender_alertUnconfirmed(t *testing.T) {
 	txStore := txmgrtest.NewTestTxStore(t, db)
 
 	originalBroadcastAt := time.Unix(1616509100, 0)
-	er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, big.NewInt(0), lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
+	er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, testutils.FixtureChainID, lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
 
 	t.Run("alerts only once for unconfirmed transaction attempt within the unconfirmedTxAlertDelay duration", func(t *testing.T) {
 		_ = txmgrtest.MustInsertUnconfirmedEthTxWithBroadcastLegacyAttempt(t, txStore, int64(1), fromAddress, originalBroadcastAt)
@@ -153,7 +152,7 @@ func Test_EthResender_Start(t *testing.T) {
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 	lggr := logger.Test(t)
 
 	t.Run("resends transactions that have been languishing unconfirmed for too long", func(t *testing.T) {
@@ -161,7 +160,7 @@ func Test_EthResender_Start(t *testing.T) {
 		ethClient := clienttest.NewClientWithDefaultChainID(t)
 		ethClient.On("IsL2").Return(false).Maybe()
 
-		er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, big.NewInt(0), lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
+		er := txmgr.NewEvmResender(lggr, txStore, txmgr.NewEvmTxmClient(ethClient, nil), txmgr.NewEvmTracker(txStore, ethKeyStore, testutils.FixtureChainID, lggr), ethKeyStore, 100*time.Millisecond, ccfg.EVM(), ccfg.EVM().Transactions())
 
 		originalBroadcastAt := time.Unix(1616509100, 0)
 		etx := txmgrtest.MustInsertUnconfirmedEthTxWithBroadcastLegacyAttempt(t, txStore, 0, fromAddress, originalBroadcastAt)
diff --git a/pkg/txmgr/tracker_test.go b/pkg/txmgr/tracker_test.go
index 7480a851e7..61352efce6 100644
--- a/pkg/txmgr/tracker_test.go
+++ b/pkg/txmgr/tracker_test.go
@@ -23,7 +23,7 @@ import (
 func newTestEvmTrackerSetup(t *testing.T) (*txmgr.Tracker, txmgr.TestEvmTxStore) {
 	db := testutils.NewSqlxDB(t)
 	txStore := txmgrtest.NewTestTxStore(t, db)
-	chainID := big.NewInt(0)
+	chainID := testutils.FixtureChainID
 	memKS := keystest.NewMemoryChainStore()
 	addr1 := memKS.MustCreate(t)
 	addr2 := memKS.MustCreate(t)
diff --git a/pkg/txmgr/txmgr_test.go b/pkg/txmgr/txmgr_test.go
index 9ae4f1c866..84e35b697d 100644
--- a/pkg/txmgr/txmgr_test.go
+++ b/pkg/txmgr/txmgr_test.go
@@ -107,7 +107,7 @@ func TestTxm_SendNativeToken_DoesNotSendToZero(t *testing.T) {
 	txm, err := makeTestEvmTxm(t, db, ethClient, estimator, evmConfig, evmConfig.GasEstimator(), evmConfig.Transactions(), dbConfig, dbConfig.Listener(), &keystest.FakeChainStore{})
 	require.NoError(t, err)
 
-	_, err = txm.SendNativeToken(tests.Context(t), big.NewInt(0), from, to, *value, 21000)
+	_, err = txm.SendNativeToken(t.Context(), testutils.FixtureChainID, from, to, *value, 21000)
 	require.Error(t, err)
 	require.EqualError(t, err, "cannot send native token to zero address")
 }
@@ -119,7 +119,7 @@ func TestTxm_CreateTransaction(t *testing.T) {
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	toAddress := testutils.NewAddress()
 	gasLimit := uint64(1000)
@@ -395,7 +395,7 @@ func BenchmarkCreateTransaction(b *testing.B) {
 	config, dbConfig, evmConfig := txmgr.MakeTestConfigs(b)
 
 	ethClient := clienttest.NewClient(b)
-	ethClient.On("ConfiguredChainID").Return(big.NewInt(0)).Maybe()
+	ethClient.On("ConfiguredChainID").Return(testutils.FixtureChainID).Maybe()
 
 	estimator, err := gas.NewEstimator(logger.Test(b), ethClient, config.ChainType(), ethClient.ConfiguredChainID(), evmConfig.GasEstimator(), nil)
 	require.NoError(b, err)
@@ -433,7 +433,7 @@ func TestTxm_CreateTransaction_OutOfEth(t *testing.T) {
 	memKS := keystest.NewMemoryChainStore()
 	fromAddress := memKS.MustCreate(t)
 	otherAddress := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	gasLimit := uint64(1000)
 	toAddress := testutils.NewAddress()
@@ -567,7 +567,7 @@ func TestTxm_Reset(t *testing.T) {
 	memKS := keystest.NewMemoryChainStore()
 	addr := memKS.MustCreate(t)
 	addr2 := memKS.MustCreate(t)
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	// 4 confirmed tx from addr1
@@ -632,7 +632,7 @@ func TestTxm_GetTransactionFee(t *testing.T) {
 	db := testutils.NewSqlxDB(t)
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 	feeLimit := uint64(10_000)
 
 	_, dbConfig, evmConfig := txmgr.MakeTestConfigs(t)
@@ -678,6 +678,7 @@ func TestTxm_GetTransactionFee(t *testing.T) {
 			EncodedPayload: []byte{1, 2, 3},
 			FeeLimit:       feeLimit,
 			State:          txmgrcommon.TxUnstarted,
+			ChainID:        testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -710,6 +711,7 @@ func TestTxm_GetTransactionFee(t *testing.T) {
 			State:              txmgrcommon.TxFinalized,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -737,7 +739,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 	db := testutils.NewSqlxDB(t)
 	txStore := txmgrtest.NewTestTxStore(t, db)
 	memKS := keystest.NewMemoryChainStore()
-	ethKeyStore := keys.NewChainStore(memKS, big.NewInt(0))
+	ethKeyStore := keys.NewChainStore(memKS, testutils.FixtureChainID)
 	feeLimit := uint64(10_000)
 
 	_, dbConfig, evmConfig := txmgr.MakeTestConfigs(t)
@@ -784,6 +786,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			EncodedPayload: []byte{1, 2, 3},
 			FeeLimit:       feeLimit,
 			State:          txmgrcommon.TxUnstarted,
+			ChainID:        testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -803,6 +806,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			EncodedPayload: []byte{1, 2, 3},
 			FeeLimit:       feeLimit,
 			State:          txmgrcommon.TxInProgress,
+			ChainID:        testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -825,6 +829,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			State:              txmgrcommon.TxUnconfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -847,6 +852,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			State:              txmgrcommon.TxConfirmed,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -876,6 +882,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			State:              txmgrcommon.TxFinalized,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -905,6 +912,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			State:              txmgrcommon.TxConfirmedMissingReceipt,
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -929,6 +937,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			Error:              null.NewString(evmclient.TerminallyStuckMsg, true),
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -951,6 +960,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			Error:              null.NewString(terminallyStuckClientError, true),
 			BroadcastAt:        &broadcast,
 			InitialBroadcastAt: &broadcast,
+			ChainID:            testutils.FixtureChainID,
 		}
 		err = txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -971,6 +981,7 @@ func TestTxm_GetTransactionStatus(t *testing.T) {
 			FeeLimit:       feeLimit,
 			State:          txmgrcommon.TxFatalError,
 			Error:          null.NewString(errorMsg, true),
+			ChainID:        testutils.FixtureChainID,
 		}
 		err := txStore.InsertTx(ctx, tx)
 		require.NoError(t, err)
@@ -1065,7 +1076,7 @@ func mustInsertUnconfirmedEthTxWithBroadcastDynamicFeeAttempt(t *testing.T, txSt
 
 	addr := testutils.NewAddress()
 	dtx := types.DynamicFeeTx{
-		ChainID:   big.NewInt(0),
+		ChainID:   testutils.FixtureChainID,
 		Nonce:     uint64(nonce),
 		GasTipCap: big.NewInt(1),
 		GasFeeCap: big.NewInt(1),
@@ -1127,6 +1138,7 @@ func mustInsertConfirmedMissingReceiptEthTxWithLegacyAttempt(
 	require.NoError(t, txStore.InsertTx(ctx, &etx))
 	attempt := txmgrtest.NewLegacyEthTxAttempt(t, etx.ID)
 	attempt.BroadcastBeforeBlockNum = &broadcastBeforeBlockNum
+	attempt.Tx.ChainID = testutils.FixtureChainID
 	attempt.State = txmgrtypes.TxAttemptBroadcast
 	require.NoError(t, txStore.InsertTxAttempt(ctx, &attempt))
 	etx.TxAttempts = append(etx.TxAttempts, attempt)
@@ -1145,6 +1157,7 @@ func mustInsertInProgressEthTxWithAttempt(t testing.TB, txStore txmgr.TestEvmTxS
 	rlp := new(bytes.Buffer)
 	require.NoError(t, tx.EncodeRLP(rlp))
 	attempt.SignedRawTx = rlp.Bytes()
+	attempt.Tx.ChainID = testutils.FixtureChainID
 	attempt.State = txmgrtypes.TxAttemptInProgress
 	require.NoError(t, txStore.InsertTxAttempt(ctx, &attempt))
 	var err error
diff --git a/pkg/txmgr/txmgrtest/utils.go b/pkg/txmgr/txmgrtest/utils.go
index 54f337d001..8a6e926347 100644
--- a/pkg/txmgr/txmgrtest/utils.go
+++ b/pkg/txmgr/txmgrtest/utils.go
@@ -35,6 +35,7 @@ func NewEthTx(fromAddress common.Address) txmgr.Tx {
 		Value:          big.Int(assets.NewEthValue(142)),
 		FeeLimit:       uint64(1000000000),
 		State:          txmgrcommon.TxUnstarted,
+		ChainID:        evmtestutils.FixtureChainID,
 	}
 }
 
diff --git a/pkg/types/utils.go b/pkg/types/utils.go
index 96e0a02e2c..33c5f0f9cd 100644
--- a/pkg/types/utils.go
+++ b/pkg/types/utils.go
@@ -13,3 +13,8 @@ func MustGetABI(json string) abi.ABI {
 	}
 	return abi
 }
+
+// NullClientChainID is set to a chainID that is unlikely to be used in production.
+// It cannot be zero due to a breaking change in go-ethereum:
+// https://github.com/ethereum/go-ethereum/blob/master/core/types/transaction_signing.go#L193
+const NullClientChainID = 1399100