diff --git a/pkg/bbgo/environment.go b/pkg/bbgo/environment.go
index f82dc4e4f..c2bda78d6 100644
--- a/pkg/bbgo/environment.go
+++ b/pkg/bbgo/environment.go
@@ -194,6 +194,7 @@ func (environ *Environment) Init(ctx context.Context) (err error) {
 
 				// update last prices by the given kline
 				lastKLine := kLines[len(kLines)-1]
+				log.Infof("last kline: %+v", lastKLine)
 				if lastPriceTime == emptyTime {
 					session.lastPrices[symbol] = lastKLine.Close
 					lastPriceTime = lastKLine.EndTime
diff --git a/pkg/indicator/ewma.go b/pkg/indicator/ewma.go
index 0690fdbff..86b332e37 100644
--- a/pkg/indicator/ewma.go
+++ b/pkg/indicator/ewma.go
@@ -19,6 +19,10 @@ type EWMA struct {
 }
 
 func (inc *EWMA) Last() float64 {
+	if len(inc.Values) == 0 {
+		return 0
+	}
+
 	return inc.Values[len(inc.Values)-1]
 }
 
diff --git a/pkg/strategy/movingstop/strategy.go b/pkg/strategy/movingstop/strategy.go
index 3bda7ba57..6e2441c29 100644
--- a/pkg/strategy/movingstop/strategy.go
+++ b/pkg/strategy/movingstop/strategy.go
@@ -202,7 +202,6 @@ func (s *Strategy) CrossRun(ctx context.Context, _ bbgo.OrderExecutionRouter, se
 
 	session.Stream.OnOrderUpdate(s.handleOrderUpdate)
 
-
 	// session.Stream.OnKLineClosed
 	sourceSession.Stream.OnKLineClosed(func(kline types.KLine) {
 		// skip k-lines from other symbols
@@ -227,7 +226,7 @@ func (s *Strategy) CrossRun(ctx context.Context, _ bbgo.OrderExecutionRouter, se
 		s.clear(ctx, session)
 	})
 
-	if lastPrice, ok := session.LastPrice(s.Symbol) ; ok {
+	if lastPrice, ok := session.LastPrice(s.Symbol); ok {
 		s.place(ctx, &orderExecutor, session, indicator, lastPrice)
 	}
 
diff --git a/pkg/types/kline.go b/pkg/types/kline.go
index b9bc123a9..b45bb67d0 100644
--- a/pkg/types/kline.go
+++ b/pkg/types/kline.go
@@ -169,7 +169,8 @@ func (k KLine) GetChange() float64 {
 }
 
 func (k KLine) String() string {
-	return fmt.Sprintf("%s %s %s Open: %.8f Close: %.8f High: %.8f Low: %.8f Volume: %.8f Change: %.4f Max Change: %.4f",
+	return fmt.Sprintf("%s %s %s %s Open: %.8f Close: %.8f High: %.8f Low: %.8f Volume: %.8f Change: %.4f Max Change: %.4f",
+		k.Exchange,
 		k.StartTime.Format("2006-01-02 15:04"),
 		k.Symbol, k.Interval, k.Open, k.Close, k.High, k.Low, k.Volume, k.GetChange(), k.GetMaxChange())
 }
@@ -346,14 +347,15 @@ func (k KLineWindow) Take(size int) KLineWindow {
 }
 
 func (k KLineWindow) Tail(size int) KLineWindow {
-	if len(k) <= size {
-		win := make(KLineWindow, len(k))
+	length := len(k)
+	if length <= size {
+		win := make(KLineWindow, length)
 		copy(win, k)
 		return win
 	}
 
 	win := make(KLineWindow, size)
-	copy(win, k[len(k)-size:])
+	copy(win, k[length-1-size:])
 	return win
 }