diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index 902d5e4..45df6a9 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -157,8 +157,9 @@
     bool                mFlushHwPending; // track requests for thread flush
 
     // for last call to getTimestamp
-    bool                mPreviousValid;
-    uint32_t            mPreviousFramesWritten;
+    bool                mPreviousTimestampValid;
+    // This is either the first timestamp or one that has passed
+    // the check to prevent retrograde motion.
     AudioTimestamp      mPreviousTimestamp;
 };  // end of Track