diff --git a/ethereum/flags.go b/ethereum/flags.go
index 58220f4e6..7924dd7bf 100644
--- a/ethereum/flags.go
+++ b/ethereum/flags.go
@@ -3,11 +3,13 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"os/user"
 	"path"
 
 	"github.com/ethereum/eth-go/ethlog"
+	"github.com/ethereum/eth-go/ethvm"
 )
 
 var (
@@ -37,6 +39,7 @@ var (
 	Dump            bool
 	DumpHash        string
 	DumpNumber      int
+	VmType          int
 )
 
 // flags specific to cli client
@@ -59,6 +62,7 @@ func Init() {
 		flag.PrintDefaults()
 	}
 
+	flag.IntVar(&VmType, "vm", 0, "Virtual Machine type: 0-1: standard, debug")
 	flag.StringVar(&Identifier, "id", "", "Custom client identifier")
 	flag.StringVar(&KeyRing, "keyring", "", "identifier for keyring to use")
 	flag.StringVar(&KeyStore, "keystore", "db", "system to store keyrings: db|file (db)")
@@ -91,5 +95,9 @@ func Init() {
 
 	flag.Parse()
 
+	if VmType >= int(ethvm.MaxVmTy) {
+		log.Fatal("Invalid VM type ", VmType)
+	}
+
 	InputFile = flag.Arg(0)
 }
diff --git a/ethereum/main.go b/ethereum/main.go
index 6a9af6b96..b8f8ce39a 100644
--- a/ethereum/main.go
+++ b/ethereum/main.go
@@ -31,7 +31,7 @@ func main() {
 		LogLevel = 0
 	}
 
-	utils.InitConfig(ConfigFile, Datadir, "ETH")
+	utils.InitConfig(VmType, ConfigFile, Datadir, "ETH")
 	ethutil.Config.Diff = DiffTool
 	ethutil.Config.DiffType = DiffType
 
diff --git a/mist/debugger.go b/mist/debugger.go
index 9d1de8c42..241635ebe 100644
--- a/mist/debugger.go
+++ b/mist/debugger.go
@@ -20,7 +20,7 @@ type DebuggerWindow struct {
 	engine *qml.Engine
 	lib    *UiLib
 
-	vm *ethvm.Vm
+	vm *ethvm.DebugVm
 	Db *Debugger
 
 	state *ethstate.State
@@ -37,7 +37,7 @@ func NewDebuggerWindow(lib *UiLib) *DebuggerWindow {
 
 	win := component.CreateWindow(nil)
 
-	w := &DebuggerWindow{engine: engine, win: win, lib: lib, vm: &ethvm.Vm{}}
+	w := &DebuggerWindow{engine: engine, win: win, lib: lib, vm: &ethvm.DebugVm{}}
 	w.Db = NewDebugger(w)
 
 	return w
@@ -135,8 +135,7 @@ func (self *DebuggerWindow) Debug(valueStr, gasStr, gasPriceStr, scriptStr, data
 
 	callerClosure := ethvm.NewClosure(&ethstate.Message{}, account, contract, script, gas, gasPrice)
 	env := utils.NewEnv(state, block, account.Address(), value)
-	vm := ethvm.New(env)
-	vm.Verbose = true
+	vm := ethvm.NewDebugVm(env)
 	vm.Dbg = self.Db
 
 	self.vm = vm
diff --git a/mist/flags.go b/mist/flags.go
index a56d689c0..5cf34c740 100644
--- a/mist/flags.go
+++ b/mist/flags.go
@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"os/user"
 	"path"
@@ -11,6 +12,7 @@ import (
 
 	"bitbucket.org/kardianos/osext"
 	"github.com/ethereum/eth-go/ethlog"
+	"github.com/ethereum/eth-go/ethvm"
 )
 
 var (
@@ -35,6 +37,7 @@ var (
 	ConfigFile      string
 	DebugFile       string
 	LogLevel        int
+	VmType          int
 )
 
 // flags specific to gui client
@@ -78,6 +81,7 @@ func Init() {
 		flag.PrintDefaults()
 	}
 
+	flag.IntVar(&VmType, "vm", 0, "Virtual Machine type: 0-1: standard, debug")
 	flag.StringVar(&Identifier, "id", "", "Custom client identifier")
 	flag.StringVar(&KeyRing, "keyring", "", "identifier for keyring to use")
 	flag.StringVar(&KeyStore, "keystore", "db", "system to store keyrings: db|file (db)")
@@ -101,4 +105,8 @@ func Init() {
 	flag.StringVar(&AssetPath, "asset_path", defaultAssetPath(), "absolute path to GUI assets directory")
 
 	flag.Parse()
+
+	if VmType >= int(ethvm.MaxVmTy) {
+		log.Fatal("Invalid VM type ", VmType)
+	}
 }
diff --git a/mist/main.go b/mist/main.go
index 12f8681cf..54c4d4501 100644
--- a/mist/main.go
+++ b/mist/main.go
@@ -21,7 +21,7 @@ func run() error {
 	// precedence: code-internal flag default < config file < environment variables < command line
 	Init() // parsing command line
 
-	config := utils.InitConfig(ConfigFile, Datadir, "ETH")
+	config := utils.InitConfig(VmType, ConfigFile, Datadir, "ETH")
 
 	utils.InitDataDir(Datadir)
 
diff --git a/utils/cmd.go b/utils/cmd.go
index 700542cae..060e8067b 100644
--- a/utils/cmd.go
+++ b/utils/cmd.go
@@ -118,9 +118,12 @@ func InitLogging(Datadir string, LogFile string, LogLevel int, DebugFile string)
 	return sys
 }
 
-func InitConfig(ConfigFile string, Datadir string, EnvPrefix string) *ethutil.ConfigManager {
+func InitConfig(vmType int, ConfigFile string, Datadir string, EnvPrefix string) *ethutil.ConfigManager {
 	InitDataDir(Datadir)
-	return ethutil.ReadConfig(ConfigFile, Datadir, EnvPrefix)
+	cfg := ethutil.ReadConfig(ConfigFile, Datadir, EnvPrefix)
+	cfg.VmType = vmType
+
+	return cfg
 }
 
 func exit(err error) {