diff --git a/webrtc/modules/audio_device/ios/voice_processing_audio_unit.mm b/webrtc/modules/audio_device/ios/voice_processing_audio_unit.mm
index a9d599a0c4..3bb4daabe8 100644
--- a/webrtc/modules/audio_device/ios/voice_processing_audio_unit.mm
+++ b/webrtc/modules/audio_device/ios/voice_processing_audio_unit.mm
@@ -155,7 +155,7 @@ static void LogStreamDescription(AudioStreamBasicDescription description) {
   input_callback.inputProcRefCon = this;
   result = AudioUnitSetProperty(vpio_unit_,
                                 kAudioOutputUnitProperty_SetInputCallback,
-                                kAudioUnitScope_Global, kInputBus,
+                                kAudioUnitScope_Global, kOutputBus, // kAudioUnitScope_Global only one bus == 0 
                                 &input_callback, sizeof(input_callback));
   if (result != noErr) {
     DisposeAudioUnit();