diff --git a/eth/gasprice/feehistory.go b/eth/gasprice/feehistory.go
index 6ddcab73a..7d29350c4 100644
--- a/eth/gasprice/feehistory.go
+++ b/eth/gasprice/feehistory.go
@@ -132,6 +132,11 @@ func (oracle *Oracle) processBlock(bf *blockFees, percentiles []float64) {
 	sorter := make(sortGasAndReward, len(bf.block.Transactions()))
 	for i, tx := range bf.block.Transactions() {
 		reward, _ := tx.EffectiveGasTip(bf.block.BaseFee())
+		// Only system transaction may result in negative reward.
+		// Fix it up by setting the reward to 0.
+		if reward.Sign() == -1 {
+			reward = common.Big0
+		}
 		sorter[i] = txGasAndReward{gasUsed: bf.receipts[i].GasUsed, reward: reward}
 	}
 	sort.Sort(sorter)