diff --git a/params/config.go b/params/config.go
index a00e885c49..2503e41ffc 100644
--- a/params/config.go
+++ b/params/config.go
@@ -166,7 +166,7 @@ type UpgradeConfig struct {
 	// Config for optional timestamps that enable network upgrades.
 	// Note: if OptionalUpgrades is specified in the JSON all previously activated
 	// forks must be present or upgradeBytes will be rejected.
-	OptionalNetworkUpgrades *OptionalNetworkUpgrades `json:"networkUpgrades,omitempty"`
+	OptionalNetworkUpgrades *OptionalNetworkUpgrades
 
 	// Config for modifying state as a network upgrade.
 	StateUpgrades []StateUpgrade `json:"stateUpgrades,omitempty"`
@@ -444,17 +444,17 @@ func (c *ChainConfig) Verify() error {
 	return nil
 }
 
-type Fork struct {
-	name      string   `serialize:"true"`
-	block     *big.Int `serialize:"true"` // some go-ethereum forks use block numbers
-	timestamp *uint64  `serialize:"true"` // Avalanche forks use timestamps
-	optional  bool     `serialize:"true"` // if true, the fork may be nil and next fork is still allowed
+type fork struct {
+	name      string
+	block     *big.Int // some go-ethereum forks use block numbers
+	timestamp *uint64  // Avalanche forks use timestamps
+	optional  bool     // if true, the fork may be nil and next fork is still allowed
 }
 
 // CheckConfigForkOrder checks that we don't "skip" any forks, geth isn't pluggable enough
 // to guarantee that forks can be implemented in a different order than on official networks
 func (c *ChainConfig) CheckConfigForkOrder() error {
-	ethForks := []Fork{
+	ethForks := []fork{
 		{name: "homesteadBlock", block: c.HomesteadBlock},
 		{name: "eip150Block", block: c.EIP150Block},
 		{name: "eip155Block", block: c.EIP155Block},
@@ -493,8 +493,8 @@ func (c *ChainConfig) CheckConfigForkOrder() error {
 
 // checkForks checks that forks are enabled in order and returns an error if not
 // [blockFork] is true if the fork is a block number fork, false if it is a timestamp fork
-func checkForks(forks []Fork, blockFork bool) error {
-	lastFork := Fork{}
+func checkForks(forks []fork, blockFork bool) error {
+	lastFork := fork{}
 	for _, cur := range forks {
 		if blockFork && cur.block != nil && common.Big0.Cmp(cur.block) != 0 {
 			return errNonGenesisForkByHeight
diff --git a/params/network_upgrades.go b/params/network_upgrades.go
index 916762d8d9..9cec00ba33 100644
--- a/params/network_upgrades.go
+++ b/params/network_upgrades.go
@@ -4,6 +4,8 @@
 package params
 
 import (
+	"math/big"
+
 	"github.com/ava-labs/subnet-evm/utils"
 )
 
@@ -50,21 +52,44 @@ func (m *MandatoryNetworkUpgrades) CheckMandatoryCompatible(newcfg *MandatoryNet
 	return nil
 }
 
-func (m *MandatoryNetworkUpgrades) mandatoryForkOrder() []Fork {
-	return []Fork{
+func (m *MandatoryNetworkUpgrades) mandatoryForkOrder() []fork {
+	return []fork{
 		{name: "subnetEVMTimestamp", timestamp: m.SubnetEVMTimestamp},
 		{name: "dUpgradeTimestamp", timestamp: m.DUpgradeTimestamp},
 	}
 }
 
+type OptionalFork struct {
+	Name      string  `json:"name" serialize:"true"`
+	Block     big.Int `json:"block" serialize:"true"`
+	Timestamp uint64  `json:"timestamp" serialize:"true"`
+}
+
 type OptionalNetworkUpgrades struct {
-	Updates []Fork `json:"serialize,omitempty" serialize:"true"`
+	OptionalNetworkUpgrades []OptionalFork `json:"networkUpgrades,omitempty" serialize:"true"`
 }
 
 func (n *OptionalNetworkUpgrades) CheckOptionalCompatible(newcfg *OptionalNetworkUpgrades, time uint64) *ConfigCompatError {
 	return nil
 }
 
-func (n *OptionalNetworkUpgrades) optionalForkOrder() []Fork {
-	return n.Updates
+func (n *OptionalNetworkUpgrades) optionalForkOrder() []fork {
+	forks := make([]fork, len(n.OptionalNetworkUpgrades))
+	for i, n := range n.OptionalNetworkUpgrades {
+		var block *big.Int
+		var timestamp *uint64
+		if n.Block.BitLen() > 0 {
+			block = &n.Block
+		}
+		if n.Timestamp != 0 {
+			timestamp = &n.Timestamp
+		}
+		forks[i] = fork{
+			name:      n.Name,
+			block:     block,
+			timestamp: timestamp,
+			optional:  true,
+		}
+	}
+	return []fork{}
 }
diff --git a/plugin/evm/message/handshake/upgrade_config.go b/plugin/evm/message/handshake/upgrade_config.go
index 9ee72d9525..6599d4e054 100644
--- a/plugin/evm/message/handshake/upgrade_config.go
+++ b/plugin/evm/message/handshake/upgrade_config.go
@@ -15,7 +15,7 @@ type rawPrecompileUpgrade struct {
 }
 
 type networkUpgradeConfigMessage struct {
-	OptionalNetworkUpgrades []params.Fork `serialize:"true"`
+	OptionalNetworkUpgrades params.OptionalNetworkUpgrades `serialize:"true"`
 
 	// Config for modifying state as a network upgrade.
 	StateUpgrades []params.StateUpgrade `serialize:"true"`
@@ -64,7 +64,7 @@ func ParseUpgradeConfigMessage(bytes []byte) (*params.UpgradeConfig, error) {
 	}
 
 	return &params.UpgradeConfig{
-		OptionalNetworkUpgrades: &params.OptionalNetworkUpgrades{Updates: config.OptionalNetworkUpgrades},
+		OptionalNetworkUpgrades: &config.OptionalNetworkUpgrades,
 		StateUpgrades:           config.StateUpgrades,
 		PrecompileUpgrades:      PrecompileUpgrades,
 	}, nil
@@ -92,16 +92,17 @@ func UpgradeConfigToNetworkMessage(config *params.UpgradeConfig) (*UpgradeConfig
 		})
 	}
 
-	optionalNetworkUpgrades := make([]params.Fork, 0)
-	if config.OptionalNetworkUpgrades != nil {
-		optionalNetworkUpgrades = config.OptionalNetworkUpgrades.Updates
+	optionalNetworkUpgrades := config.OptionalNetworkUpgrades
+	if optionalNetworkUpgrades == nil {
+		optionalNetworkUpgrades = &params.OptionalNetworkUpgrades{}
 	}
 
 	wrappedConfig := networkUpgradeConfigMessage{
-		OptionalNetworkUpgrades: optionalNetworkUpgrades,
+		OptionalNetworkUpgrades: *optionalNetworkUpgrades,
 		StateUpgrades:           config.StateUpgrades,
 		PrecompileUpgrades:      PrecompileUpgrades,
 	}
+
 	bytes, err := Codec.Marshal(Version, wrappedConfig)
 	if err != nil {
 		return nil, err
diff --git a/plugin/evm/message/handshake/upgrade_config_test.go b/plugin/evm/message/handshake/upgrade_config_test.go
index 17bb449078..cc289a3880 100644
--- a/plugin/evm/message/handshake/upgrade_config_test.go
+++ b/plugin/evm/message/handshake/upgrade_config_test.go
@@ -35,6 +35,10 @@ func TestSerialize(t *testing.T) {
 	config3, err := ParseUpgradeConfigMessage(message2.Bytes)
 	require.NoError(t, err)
 
+	message3, err := UpgradeConfigToNetworkMessage(config3)
+	require.NoError(t, err)
+
 	require.Equal(t, config, config3)
 	require.Equal(t, message.Hash, message2.Hash)
+	require.Equal(t, message2.Hash, message3.Hash)
 }