diff --git a/command.py b/command.py
index bdc9f09..4ed2aef 100644
--- a/command.py
+++ b/command.py
@@ -621,7 +621,7 @@ def cmd_ducking(bot, user, text, command, parameter):
     if parameter == "" or parameter == "on":
         bot.is_ducking = True
         var.db.set('bot', 'ducking', True)
-        bot.mumble.callbacks.set_callback(pymumble.c.PYMUMBLE_CLBK_SOUNDRECEIVED, bot.ducking_sound_received)
+        bot.mumble.callbacks.set_callback(pymumble.constants.PYMUMBLE_CLBK_SOUNDRECEIVED, bot.ducking_sound_received)
         bot.mumble.set_receive_sound(True)
         log.info('cmd: ducking is on')
         msg = "Ducking on."