diff --git a/services/oboeservice/AAudioMixer.h b/services/oboeservice/AAudioMixer.h
index 9155fec..a8090bc 100644
--- a/services/oboeservice/AAudioMixer.h
+++ b/services/oboeservice/AAudioMixer.h
@@ -37,7 +37,7 @@
      * @param volume
      * @return true if underflowed
      */
-    bool mix(android::FifoBuffer *fifo, float volume);
+    bool mix(int trackIndex, android::FifoBuffer *fifo, float volume);
 
     void mixPart(float *destination, float *source, int32_t numFrames, float volume);