diff --git a/ethchain/vm.go b/ethchain/vm.go
index cfedadb08d..769333649d 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -24,14 +24,10 @@ var (
 	GasTx      = big.NewInt(500)
 )
 
-func CalculateTxGas(initSize *big.Int) *big.Int {
-	totalGas := new(big.Int)
-
-	txTotalBytes := new(big.Int).Set(initSize)
-	txTotalBytes.Div(txTotalBytes, ethutil.Big32)
-	totalGas.Add(totalGas, new(big.Int).Mul(txTotalBytes, GasSStore))
-
-	return totalGas
+type Debugger interface {
+	BreakHook(step int, op OpCode, mem *Memory, stack *Stack, stateObject *StateObject) bool
+	StepHook(step int, op OpCode, mem *Memory, stack *Stack, stateObject *StateObject) bool
+	BreakPoints() []int64
 }
 
 type Vm struct {
@@ -53,14 +49,13 @@ type Vm struct {
 	err error
 
 	// Debugging
-	Hook        DebugHook
+	Dbg Debugger
+
 	BreakPoints []int64
 	Stepping    bool
 	Fn          string
 }
 
-type DebugHook func(step int, op OpCode, mem *Memory, stack *Stack, stateObject *StateObject) bool
-
 type RuntimeVars struct {
 	Origin      []byte
 	Block       *Block
@@ -754,12 +749,14 @@ func (vm *Vm) RunClosure(closure *Closure) (ret []byte, err error) {
 
 		vm.Endl()
 
-		if vm.Hook != nil {
-			for _, instrNo := range vm.BreakPoints {
-				if pc.Cmp(big.NewInt(instrNo)) == 0 || vm.Stepping {
-					vm.Stepping = true
-
-					if !vm.Hook(prevStep, op, mem, stack, closure.Object()) {
+		if vm.Dbg != nil {
+			for _, instrNo := range vm.Dbg.BreakPoints() {
+				if pc.Cmp(big.NewInt(instrNo)) == 0 {
+					if !vm.Dbg.BreakHook(prevStep, op, mem, stack, closure.Object()) {
+						return nil, nil
+					}
+				} else if vm.Stepping {
+					if !vm.Dbg.StepHook(prevStep, op, mem, stack, closure.Object()) {
 						return nil, nil
 					}
 				}
diff --git a/ethlog/loggers.go b/ethlog/loggers.go
index 9ebe590967..219c782408 100644
--- a/ethlog/loggers.go
+++ b/ethlog/loggers.go
@@ -39,7 +39,7 @@ func (msg *logMessage) send(logger LogSystem) {
 
 var logMessages chan (*logMessage)
 var logSystems []LogSystem
-var drained = true
+var quit chan bool
 
 type LogLevel uint8
 
@@ -54,6 +54,7 @@ const (
 
 // log messages are dispatched to log writers
 func start() {
+out:
 	for {
 		select {
 		case msg := <-logMessages:
@@ -62,15 +63,23 @@ func start() {
 					msg.send(logSystem)
 				}
 			}
-		default:
-			drained = true
+		case <-quit:
+			break out
 		}
 	}
 }
 
 // waits until log messages are drained (dispatched to log writers)
 func Flush() {
-	for !drained {
+	quit <- true
+
+done:
+	for {
+		select {
+		case <-logMessages:
+		default:
+			break done
+		}
 	}
 }
 
@@ -88,6 +97,7 @@ func AddLogSystem(logSystem LogSystem) {
 	defer mutex.Unlock()
 	if logSystems == nil {
 		logMessages = make(chan *logMessage)
+		quit = make(chan bool)
 		go start()
 	}
 	logSystems = append(logSystems, logSystem)
@@ -96,7 +106,6 @@ func AddLogSystem(logSystem LogSystem) {
 func (logger *Logger) sendln(level LogLevel, v ...interface{}) {
 	if logMessages != nil {
 		msg := newPrintlnLogMessage(level, logger.tag, v...)
-		drained = false
 		logMessages <- msg
 	}
 }
@@ -104,7 +113,6 @@ func (logger *Logger) sendln(level LogLevel, v ...interface{}) {
 func (logger *Logger) sendf(level LogLevel, format string, v ...interface{}) {
 	if logMessages != nil {
 		msg := newPrintfLogMessage(level, logger.tag, format, v...)
-		drained = false
 		logMessages <- msg
 	}
 }