diff --git a/core/tx_pool.go b/core/tx_pool.go
index 9f6016bc38..493d8115d2 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -586,7 +586,7 @@ func (pool *TxPool) validateTx(tx *types.Transaction, local bool) error {
 	if pool.currentState.GetBalance(from).Cmp(tx.Cost()) < 0 {
 		return ErrInsufficientFunds
 	}
-	if tx.To().String() != common.BlockSigners {
+	if tx.To() != nil && tx.To().String() != common.BlockSigners {
 		intrGas, err := IntrinsicGas(tx.Data(), tx.To() == nil, pool.homestead)
 		if err != nil {
 			return err
diff --git a/eth/backend.go b/eth/backend.go
index 7fcac749e0..c59bb5236a 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -217,7 +217,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 			if number > 0 && prevCheckpoint > 0 {
 				// Not reward for singer of genesis block and only calculate reward at checkpoint block.
 				startBlockNumber := number - (rCheckpoint * 2) + 1
-				endBlockNumber := startBlockNumber + rCheckpoint - 2
+				endBlockNumber := startBlockNumber + rCheckpoint - 1
 				signers := make(map[common.Address]*rewardLog)
 				validators := make(map[common.Address]*rewardLog)
 				totalSigner := uint64(0)