diff --git a/Alc/mixer.c b/Alc/mixer.c
index bbbfba18..5e5ba760 100644
--- a/Alc/mixer.c
+++ b/Alc/mixer.c
@@ -427,6 +427,7 @@ ALboolean MixSource(ALvoice *voice, ALsource *Source, ALCdevice *Device, ALsizei
                     {
                         const ALsizei SizeToDo = mini(SrcBufferSize - FilledAmt, LoopSize);
 
+                        CompLen = 0;
                         for(i = 0;i < BufferListItem->num_buffers;i++)
                         {
                             const ALbuffer *buffer = BufferListItem->buffers[i];