diff --git a/main.py b/main.py
index 7feb00e..775538a 100755
--- a/main.py
+++ b/main.py
@@ -117,7 +117,7 @@ class MainWindow(FloatLayout):
             if 'time' in last_point:
                 self.lastTime = float(last_point['time'])
             if 'exception' in last_point:
-		self.lastStatus = {'status' : 'error', 'message' : last_point['exception']}
+                self.lastStatus = {'status' : 'error', 'message' : last_point['exception']}
             self.lastData = data
         #if dataThreadDataQueue.qsize():
         #    Logger.debug('update_last_temperature: ' + str(dataThreadDataQueue.qsize()) + ' items left in queue after ' + str(len(data)) + ' items were taken out')
@@ -513,7 +513,11 @@ class PlotWidget(Image):
             if 'data' in point and 'time' in point and 'temperature' in point['data']:
                 points.append(numpy.array([(point['time'], point['data']['temperature'])],
                                         dtype=float, ndmin =2))
-        extra_data = numpy.vstack(tuple(points))
+        extra_data = numpy.array(list(), dtype = float)
+        if points:
+            extra_data = numpy.vstack(tuple(points))
+        if not extra_data.any():
+            return
         if not self.data.any():
             self.data = extra_data
             return