patch.diff

diff --git a/ptop/interfaces/GUI.py b/ptop/interfaces/GUI.py
index 897bef3..c045fe7 100644
--- a/ptop/interfaces/GUI.py
+++ b/ptop/interfaces/GUI.py
@@ -305,6 +305,9 @@ class PtopGUI(npyscreen.NPSApp):
         self.CHART_LENGTH = int(self.CHART_LENGTH*self.X_SCALING_FACTOR)
         self.CHART_HEIGHT = int(self.CHART_HEIGHT*self.Y_SCALING_FACTOR)
 
+        self.cpu_array = [0]*self.CHART_LENGTH
+        self.memory_array = [0]*self.CHART_LENGTH
+
         # add subwidgets to the parent widget
         self.window.edit()
 
diff --git a/ptop/plugins/memory_sensor.py b/ptop/plugins/memory_sensor.py
index 6fd11f8..0d90e3b 100644
--- a/ptop/plugins/memory_sensor.py
+++ b/ptop/plugins/memory_sensor.py
@@ -27,7 +27,12 @@ class MemorySensor(Plugin):
         smem = psutil.swap_memory()
         self.currentValue['text']['swap_memory']['total'] = int(float(smem.total)/(1024*1024))
         self.currentValue['text']['swap_memory']['active'] = int(float(smem.used)/(1024*1024))
-        self.currentValue['text']['swap_memory']['percentage'] = int(float(smem.used)/smem.total)*100
+
+        if smem.total:
+            self.currentValue['text']['swap_memory']['percentage'] = int(float(smem.used)/smem.total)*100
+        else:
+            self.currentValue['text']['swap_memory']['percentage'] = 0
+
 
 
 memory_sensor = MemorySensor(name='Memory',sensorType='chart',interval=0.5)