diff --git a/core/blockchain.go b/core/blockchain.go
index 2307c4cdd..4533fe625 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -244,6 +244,7 @@ func IsEpochBlock(block *types.Block) bool {
 }
 
 // EpochFirstBlock returns the block number of the first block of an epoch.
+// TODO: instead of using fixed epoch schedules, determine the first block by epoch changes.
 func EpochFirstBlock(epoch *big.Int) *big.Int {
 	if epoch.Cmp(big.NewInt(0)) == 0 {
 		return big.NewInt(0)
diff --git a/internal/params/config.go b/internal/params/config.go
index fe495148b..2078393a2 100644
--- a/internal/params/config.go
+++ b/internal/params/config.go
@@ -58,10 +58,10 @@ type TrustedCheckpoint struct {
 type ChainConfig struct {
 	ChainID *big.Int `json:"chainId"` // chainId identifies the current chain and is used for replay protection
 
-	CrossLinkEpoch *big.Int `json:"homesteadBlock,omitempty"`
+	CrossLinkEpoch *big.Int `json:"crossLinkEpoch,omitempty"`
 
-	EIP155Epoch *big.Int `json:"eip155Block,omitempty"` // EIP155 hard fork epoch (include EIP158 too)
-	S3Epoch     *big.Int `json:"s3Block,omitempty"`     // S3 epoch is the first epoch containing S3 mainnet and all ethereum update up to Constantinople
+	EIP155Epoch *big.Int `json:"eip155Epoch,omitempty"` // EIP155 hard fork epoch (include EIP158 too)
+	S3Epoch     *big.Int `json:"s3Epoch,omitempty"`     // S3 epoch is the first epoch containing S3 mainnet and all ethereum update up to Constantinople
 }
 
 // String implements the fmt.Stringer interface.