diff --git a/fvm/evm/emulator/config.go b/fvm/evm/emulator/config.go
index f6bc573f592..c6efaa322ba 100644
--- a/fvm/evm/emulator/config.go
+++ b/fvm/evm/emulator/config.go
@@ -50,7 +50,7 @@ func (c *Config) ChainRules() gethParams.Rules {
 // and set a proper height for the specific release based on the Flow EVM heights
 // so it could gets activated at a desired time.
 var DefaultChainConfig = &gethParams.ChainConfig{
-	ChainID: types.FlowEVMTestnetChainID, // default is testnet
+	ChainID: types.FlowEVMPreviewNetChainID,
 
 	// Fork scheduling based on block heights
 	HomesteadBlock:      bigZero,
diff --git a/fvm/evm/emulator/emulator_test.go b/fvm/evm/emulator/emulator_test.go
index d7d2f7f4f01..48d0087fdb5 100644
--- a/fvm/evm/emulator/emulator_test.go
+++ b/fvm/evm/emulator/emulator_test.go
@@ -248,7 +248,7 @@ func TestContractInteraction(t *testing.T) {
 					nonce += 1
 
 					ret := new(big.Int).SetBytes(res.ReturnedValue)
-					require.Equal(t, types.FlowEVMTestnetChainID, ret)
+					require.Equal(t, types.FlowEVMPreviewNetChainID, ret)
 				})
 			})
 
@@ -328,7 +328,7 @@ func TestContractInteraction(t *testing.T) {
 					tx := account.SignTx(
 						t,
 						gethTypes.NewTx(&gethTypes.DynamicFeeTx{
-							ChainID:   types.FlowEVMTestnetChainID,
+							ChainID:   types.FlowEVMPreviewNetChainID,
 							Nonce:     account.Nonce(),
 							GasTipCap: big.NewInt(2),
 							GasFeeCap: big.NewInt(3),
diff --git a/fvm/evm/types/chainIDs.go b/fvm/evm/types/chainIDs.go
index 50394f38a22..d979bc732a3 100644
--- a/fvm/evm/types/chainIDs.go
+++ b/fvm/evm/types/chainIDs.go
@@ -7,15 +7,19 @@ import (
 )
 
 var (
-	FlowEVMTestnetChainID = big.NewInt(646)
-	FlowEVMMainnetChainID = big.NewInt(747)
+	FlowEVMPreviewNetChainID = big.NewInt(646)
+	FlowEVMTestNetChainID    = big.NewInt(545)
+	FlowEVMMainNetChainID    = big.NewInt(747)
 )
 
 func EVMChainIDFromFlowChainID(flowChainID flow.ChainID) *big.Int {
-	// default evm chain ID is testnet
-	chainID := FlowEVMTestnetChainID
-	if flowChainID == flow.Mainnet {
-		chainID = FlowEVMMainnetChainID
+	// default evm chain ID is previewNet
+	switch flowChainID {
+	case flow.Mainnet:
+		return FlowEVMMainNetChainID
+	case flow.Testnet:
+		return FlowEVMTestNetChainID
+	default:
+		return FlowEVMPreviewNetChainID
 	}
-	return chainID
 }
diff --git a/fvm/evm/types/emulator.go b/fvm/evm/types/emulator.go
index 79b8e87960e..9a18805f309 100644
--- a/fvm/evm/types/emulator.go
+++ b/fvm/evm/types/emulator.go
@@ -39,7 +39,7 @@ type BlockContext struct {
 // NewDefaultBlockContext returns a new default block context
 func NewDefaultBlockContext(BlockNumber uint64) BlockContext {
 	return BlockContext{
-		ChainID:                FlowEVMTestnetChainID,
+		ChainID:                FlowEVMPreviewNetChainID,
 		BlockNumber:            BlockNumber,
 		DirectCallBaseGasUsage: DefaultDirectCallBaseGasUsage,
 		DirectCallGasPrice:     DefaultDirectCallGasPrice,