diff --git a/cmd/puppeth/genesis.go b/cmd/puppeth/genesis.go
index ae7675cd9b..1e283ec1b6 100644
--- a/cmd/puppeth/genesis.go
+++ b/cmd/puppeth/genesis.go
@@ -36,25 +36,27 @@ import (
 type alethGenesisSpec struct {
 	SealEngine string `json:"sealEngine"`
 	Params     struct {
-		AccountStartNonce       math2.HexOrDecimal64   `json:"accountStartNonce"`
-		MaximumExtraDataSize    hexutil.Uint64         `json:"maximumExtraDataSize"`
-		HomesteadForkBlock      hexutil.Uint64         `json:"homesteadForkBlock"`
-		DaoHardforkBlock        math2.HexOrDecimal64   `json:"daoHardforkBlock"`
-		EIP150ForkBlock         hexutil.Uint64         `json:"EIP150ForkBlock"`
-		EIP158ForkBlock         hexutil.Uint64         `json:"EIP158ForkBlock"`
-		ByzantiumForkBlock      hexutil.Uint64         `json:"byzantiumForkBlock"`
-		ConstantinopleForkBlock hexutil.Uint64         `json:"constantinopleForkBlock"`
-		MinGasLimit             hexutil.Uint64         `json:"minGasLimit"`
-		MaxGasLimit             hexutil.Uint64         `json:"maxGasLimit"`
-		TieBreakingGas          bool                   `json:"tieBreakingGas"`
-		GasLimitBoundDivisor    math2.HexOrDecimal64   `json:"gasLimitBoundDivisor"`
-		MinimumDifficulty       *hexutil.Big           `json:"minimumDifficulty"`
-		DifficultyBoundDivisor  *math2.HexOrDecimal256 `json:"difficultyBoundDivisor"`
-		DurationLimit           *math2.HexOrDecimal256 `json:"durationLimit"`
-		BlockReward             *hexutil.Big           `json:"blockReward"`
-		NetworkID               hexutil.Uint64         `json:"networkID"`
-		ChainID                 hexutil.Uint64         `json:"chainID"`
-		AllowFutureBlocks       bool                   `json:"allowFutureBlocks"`
+		AccountStartNonce          math2.HexOrDecimal64   `json:"accountStartNonce"`
+		MaximumExtraDataSize       hexutil.Uint64         `json:"maximumExtraDataSize"`
+		HomesteadForkBlock         hexutil.Uint64         `json:"homesteadForkBlock"`
+		DaoHardforkBlock           math2.HexOrDecimal64   `json:"daoHardforkBlock"`
+		EIP150ForkBlock            hexutil.Uint64         `json:"EIP150ForkBlock"`
+		EIP158ForkBlock            hexutil.Uint64         `json:"EIP158ForkBlock"`
+		ByzantiumForkBlock         hexutil.Uint64         `json:"byzantiumForkBlock"`
+		ConstantinopleForkBlock    hexutil.Uint64         `json:"constantinopleForkBlock"`
+		ConstantinopleFixForkBlock hexutil.Uint64         `json:"constantinopleFixForkBlock"`
+		IstanbulForkBlock          hexutil.Uint64         `json:"IstanbulForkBlock"`
+		MinGasLimit                hexutil.Uint64         `json:"minGasLimit"`
+		MaxGasLimit                hexutil.Uint64         `json:"maxGasLimit"`
+		TieBreakingGas             bool                   `json:"tieBreakingGas"`
+		GasLimitBoundDivisor       math2.HexOrDecimal64   `json:"gasLimitBoundDivisor"`
+		MinimumDifficulty          *hexutil.Big           `json:"minimumDifficulty"`
+		DifficultyBoundDivisor     *math2.HexOrDecimal256 `json:"difficultyBoundDivisor"`
+		DurationLimit              *math2.HexOrDecimal256 `json:"durationLimit"`
+		BlockReward                *hexutil.Big           `json:"blockReward"`
+		NetworkID                  hexutil.Uint64         `json:"networkID"`
+		ChainID                    hexutil.Uint64         `json:"chainID"`
+		AllowFutureBlocks          bool                   `json:"allowFutureBlocks"`
 	} `json:"params"`
 
 	Genesis struct {
@@ -112,15 +114,27 @@ func newAlethGenesisSpec(network string, genesis *core.Genesis) (*alethGenesisSp
 	spec.Params.EIP150ForkBlock = (hexutil.Uint64)(genesis.Config.EIP150Block.Uint64())
 	spec.Params.EIP158ForkBlock = (hexutil.Uint64)(genesis.Config.EIP158Block.Uint64())
 
-	// Byzantium
+	if num := genesis.Config.HomesteadBlock; num != nil {
+		spec.Params.HomesteadForkBlock = hexutil.Uint64(num.Uint64())
+	}
+	if num := genesis.Config.EIP150Block; num != nil {
+		spec.Params.EIP150ForkBlock = hexutil.Uint64(num.Uint64())
+	}
+	if num := genesis.Config.EIP158Block; num != nil {
+		spec.Params.EIP158ForkBlock = hexutil.Uint64(num.Uint64())
+	}
 	if num := genesis.Config.ByzantiumBlock; num != nil {
-		spec.setByzantium(num)
+		spec.Params.ByzantiumForkBlock = hexutil.Uint64(num.Uint64())
 	}
-	// Constantinople
 	if num := genesis.Config.ConstantinopleBlock; num != nil {
-		spec.setConstantinople(num)
+		spec.Params.ConstantinopleForkBlock = hexutil.Uint64(num.Uint64())
+	}
+	if num := genesis.Config.PetersburgBlock; num != nil {
+		spec.Params.ConstantinopleFixForkBlock = hexutil.Uint64(num.Uint64())
+	}
+	if num := genesis.Config.IstanbulBlock; num != nil {
+		spec.Params.IstanbulForkBlock = hexutil.Uint64(num.Uint64())
 	}
-
 	spec.Params.NetworkID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())
 	spec.Params.ChainID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())
 	spec.Params.MaximumExtraDataSize = (hexutil.Uint64)(params.MaximumExtraDataSize)
@@ -196,14 +210,6 @@ func (spec *alethGenesisSpec) setAccount(address common.Address, account core.Ge
 
 }
 
-func (spec *alethGenesisSpec) setByzantium(num *big.Int) {
-	spec.Params.ByzantiumForkBlock = hexutil.Uint64(num.Uint64())
-}
-
-func (spec *alethGenesisSpec) setConstantinople(num *big.Int) {
-	spec.Params.ConstantinopleForkBlock = hexutil.Uint64(num.Uint64())
-}
-
 // parityChainSpec is the chain specification format used by Parity.
 type parityChainSpec struct {
 	Name    string `json:"name"`
diff --git a/cmd/puppeth/wizard_genesis.go b/cmd/puppeth/wizard_genesis.go
index 499f320f64..44b607ce86 100644
--- a/cmd/puppeth/wizard_genesis.go
+++ b/cmd/puppeth/wizard_genesis.go
@@ -51,6 +51,7 @@ func (w *wizard) makeGenesis() {
 			ByzantiumBlock:      big.NewInt(0),
 			ConstantinopleBlock: big.NewInt(0),
 			PetersburgBlock:     big.NewInt(0),
+			IstanbulBlock:       big.NewInt(0),
 		},
 	}
 	// Figure out which consensus engine to choose
@@ -230,6 +231,10 @@ func (w *wizard) manageGenesis() {
 		fmt.Printf("Which block should Petersburg come into effect? (default = %v)\n", w.conf.Genesis.Config.PetersburgBlock)
 		w.conf.Genesis.Config.PetersburgBlock = w.readDefaultBigInt(w.conf.Genesis.Config.PetersburgBlock)
 
+		fmt.Println()
+		fmt.Printf("Which block should Istanbul come into effect? (default = %v)\n", w.conf.Genesis.Config.IstanbulBlock)
+		w.conf.Genesis.Config.IstanbulBlock = w.readDefaultBigInt(w.conf.Genesis.Config.IstanbulBlock)
+
 		out, _ := json.MarshalIndent(w.conf.Genesis.Config, "", "  ")
 		fmt.Printf("Chain configuration updated:\n\n%s\n", out)
 
@@ -268,7 +273,7 @@ func (w *wizard) manageGenesis() {
 		} else {
 			saveGenesis(folder, w.network, "parity", spec)
 		}
-		// Export the genesis spec used by Harmony (formerly EthereumJ
+		// Export the genesis spec used by Harmony (formerly EthereumJ)
 		saveGenesis(folder, w.network, "harmony", w.conf.Genesis)
 
 	case "3":