diff --git a/mopidy/mixer.py b/mopidy/mixer.py
index cd70d78a..34e006a4 100644
--- a/mopidy/mixer.py
+++ b/mopidy/mixer.py
@@ -115,19 +115,19 @@ class Mixer(object):
         changed, and events needs to be sent.
         """
 
-        if not hasattr(self, '_last_volume'):
-            self._last_volume = None
-        if not hasattr(self, '_last_mute'):
-            self._last_mute = None
+        if not hasattr(self, '__last_volume'):
+            self.__last_volume = None
+        if not hasattr(self, '__last_mute'):
+            self.__last_mute = None
 
-        old_volume, self._last_volume = self._last_volume, self.get_volume()
-        old_mute, self._last_mute = self._last_mute, self.get_mute()
+        old_volume, self.__last_volume = self.__last_volume, self.get_volume()
+        old_mute, self.__last_mute = self.__last_mute, self.get_mute()
 
-        if old_volume != self._last_volume:
-            self.trigger_volume_changed(self._last_volume)
+        if old_volume != self.__last_volume:
+            self.trigger_volume_changed(self.__last_volume)
 
-        if old_mute != self._last_mute:
-            self.trigger_mute_changed(self._last_mute)
+        if old_mute != self.__last_mute:
+            self.trigger_mute_changed(self.__last_mute)
 
 
 class MixerListener(listener.Listener):