diff --git a/pkg/core/native/native_gas.go b/pkg/core/native/native_gas.go
index 159e7b152..3f1159a77 100644
--- a/pkg/core/native/native_gas.go
+++ b/pkg/core/native/native_gas.go
@@ -108,7 +108,8 @@ func (g *GAS) Initialize(ic *interop.Context) error {
 	if err := g.nep17TokenNative.Initialize(ic); err != nil {
 		return err
 	}
-	if g.nep17TokenNative.getTotalSupply(ic.DAO).Sign() != 0 {
+	_, totalSupply := g.nep17TokenNative.getTotalSupply(ic.DAO)
+	if totalSupply.Sign() != 0 {
 		return errors.New("already initialized")
 	}
 	h, err := getStandbyValidatorsHash(ic)
diff --git a/pkg/core/native/native_neo.go b/pkg/core/native/native_neo.go
index 644188aac..391525f1f 100644
--- a/pkg/core/native/native_neo.go
+++ b/pkg/core/native/native_neo.go
@@ -189,7 +189,8 @@ func (n *NEO) Initialize(ic *interop.Context) error {
 		return err
 	}
 
-	if n.nep17TokenNative.getTotalSupply(ic.DAO).Sign() != 0 {
+	_, totalSupply := n.nep17TokenNative.getTotalSupply(ic.DAO)
+	if totalSupply.Sign() != 0 {
 		return errors.New("already initialized")
 	}
 
@@ -977,7 +978,8 @@ func (n *NEO) computeCommitteeMembers(bc blockchainer.Blockchainer, d dao.DAO) (
 	votersCount := bigint.FromBytes(si)
 	// votersCount / totalSupply must be >= 0.2
 	votersCount.Mul(votersCount, big.NewInt(effectiveVoterTurnout))
-	voterTurnout := votersCount.Div(votersCount, n.getTotalSupply(d))
+	_, totalSupply := n.getTotalSupply(d)
+	voterTurnout := votersCount.Div(votersCount, totalSupply)
 
 	sbVals := bc.GetStandByCommittee()
 	count := len(sbVals)
diff --git a/pkg/core/native/native_nep17.go b/pkg/core/native/native_nep17.go
index f08dd0aa1..3b2695fa8 100644
--- a/pkg/core/native/native_nep17.go
+++ b/pkg/core/native/native_nep17.go
@@ -95,19 +95,21 @@ func (c *nep17TokenNative) Decimals(_ *interop.Context, _ []stackitem.Item) stac
 }
 
 func (c *nep17TokenNative) TotalSupply(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
-	return stackitem.NewBigInteger(c.getTotalSupply(ic.DAO))
+	_, supply := c.getTotalSupply(ic.DAO)
+	return stackitem.NewBigInteger(supply)
 }
 
-func (c *nep17TokenNative) getTotalSupply(d dao.DAO) *big.Int {
+func (c *nep17TokenNative) getTotalSupply(d dao.DAO) (state.StorageItem, *big.Int) {
 	si := d.GetStorageItem(c.ID, totalSupplyKey)
 	if si == nil {
-		return big.NewInt(0)
+		si = []byte{}
 	}
-	return bigint.FromBytes(si)
+	return si, bigint.FromBytes(si)
 }
 
-func (c *nep17TokenNative) saveTotalSupply(d dao.DAO, supply *big.Int) error {
-	return d.PutStorageItem(c.ID, totalSupplyKey, bigint.ToBytes(supply))
+func (c *nep17TokenNative) saveTotalSupply(d dao.DAO, si state.StorageItem, supply *big.Int) error {
+	si = state.StorageItem(bigint.ToPreallocatedBytes(supply, si))
+	return d.PutStorageItem(c.ID, totalSupplyKey, si)
 }
 
 func (c *nep17TokenNative) Transfer(ic *interop.Context, args []stackitem.Item) stackitem.Item {
@@ -283,9 +285,9 @@ func (c *nep17TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount
 		panic(err)
 	}
 
-	supply := c.getTotalSupply(ic.DAO)
+	buf, supply := c.getTotalSupply(ic.DAO)
 	supply.Add(supply, amount)
-	err = c.saveTotalSupply(ic.DAO, supply)
+	err = c.saveTotalSupply(ic.DAO, buf, supply)
 	if err != nil {
 		panic(err)
 	}