diff --git a/device/hashrate.go b/device/hashrate.go
index e010344..cc6672d 100644
--- a/device/hashrate.go
+++ b/device/hashrate.go
@@ -63,6 +63,9 @@ func NewHashrateLog() *HashrateLogTable {
 func (h *HashrateLogTable) loopPrintHashrate() {
 	for {
 		<-h.hsrtc.C
+		if h.current_blk == nil {
+			continue
+		}
 		var hei = h.current_blk.GetHeight()
 		var lphr = difficulty.ConvertHashToRate(hei, h.period_max_power_hash, h.blktm)
 		h.hxrate_show_count++
@@ -73,6 +76,9 @@ func (h *HashrateLogTable) loopPrintHashrate() {
 		h.logts[5] = average_hashrate
 		var ratio = big.NewFloat(float64(100))
 		ratio = ratio.Mul(ratio, big.NewFloat(0).SetInt(average_lphr))
+		if h.blk_rate.Sign() == 0 {
+			continue
+		}
 		ratio = ratio.Quo(ratio, big.NewFloat(0).SetInt(h.blk_rate))
 		percentf, _ := ratio.Float64()
 		h.logts[3] = fmt.Sprintf("%.6f%%", percentf)
diff --git a/memtxpool/check.go b/memtxpool/check.go
index 59643fd..cb76be8 100644
--- a/memtxpool/check.go
+++ b/memtxpool/check.go
@@ -26,7 +26,7 @@ func (p *MemTxPool) checkDiamondCreate(newtx interfaces.Transaction, act *action
 		return fmt.Errorf("diamond create tx %s timestamp cannot more than now.", txhxhex)
 	}
 	// fee purity
-	if newtx.FeePurity() < mint.MinTransactionFeePurityOfOneByte {
+	if newtx.FeePurity() < mint.MinTransactionFeePurity {
 		return fmt.Errorf("diamond create tx %s handling fee is too low for miners to accept.", txhxhex)
 	}
 	// sign
diff --git a/memtxpool/item.go b/memtxpool/item.go
index 14c1266..603d109 100644
--- a/memtxpool/item.go
+++ b/memtxpool/item.go
@@ -10,7 +10,7 @@ type TxItem struct {
 	tx        interfaces.Transaction
 	hash      fields.Hash
 	size      uint32
-	feepurity uint64
+	feepurity uint32
 
 	next *TxItem
 	prev *TxItem