diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index ccddc5cb0..90afd7986 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -28,8 +28,8 @@
   To highlight this deliniation, the file is divided into three parts
   based on what thread context each function is intended to run in.
 
-  \par EXPERIMENTAL_MIDI_PLAYBACK
-  If EXPERIMENTAL_MIDI_PLAYBACK is defined, this class also manages
+  \par EXPERIMENTAL_MIDI_OUT
+  If EXPERIMENTAL_MIDI_OUT is defined, this class also manages
   MIDI playback. The reason for putting MIDI here rather than in, say,
   class MidiIO, is that there is no high-level synchronization and
   transport architecture, so Audio and MIDI must be coupled in order
@@ -3897,7 +3897,7 @@ void AudioIO::FillMidiBuffers()
          hasSolo = true;
          break;
       }
-   int numMidiPlaybackTracks = gAudioIO->mMidiPlaybackTracks.size();
+   auto numMidiPlaybackTracks = gAudioIO->mMidiPlaybackTracks.size();
    for(unsigned t = 0; t < numMidiPlaybackTracks; t++ )
       if( gAudioIO->mMidiPlaybackTracks[t]->GetSolo() ) {
          hasSolo = true;
@@ -4370,7 +4370,7 @@ int audacityAudioCallback(const void *inputBuffer, void *outputBuffer,
             if( gAudioIO->mPlaybackTracks[t]->GetSolo() )
                numSolo++;
 #ifdef EXPERIMENTAL_MIDI_OUT
-         int numMidiPlaybackTracks = gAudioIO->mMidiPlaybackTracks.size();
+         auto numMidiPlaybackTracks = gAudioIO->mMidiPlaybackTracks.size();
          for( unsigned t = 0; t < numMidiPlaybackTracks; t++ )
             if( gAudioIO->mMidiPlaybackTracks[t]->GetSolo() )
                numSolo++;
diff --git a/src/NoteTrack.cpp b/src/NoteTrack.cpp
index 27b770469..f18931d01 100644
--- a/src/NoteTrack.cpp
+++ b/src/NoteTrack.cpp
@@ -239,7 +239,7 @@ void NoteTrack::WarpAndTransposeNotes(double t0, double t1,
 
 
 
-int NoteTrack::DrawLabelControls(wxDC & dc, wxRect & r)
+int NoteTrack::DrawLabelControls(wxDC & dc, const wxRect &r)
 {
    int wid = 23;
    int ht = 16;
@@ -328,7 +328,7 @@ int NoteTrack::DrawLabelControls(wxDC & dc, wxRect & r)
    return box.GetBottom();
 }
 
-bool NoteTrack::LabelClick(wxRect & r, int mx, int my, bool right)
+bool NoteTrack::LabelClick(const wxRect &r, int mx, int my, bool right)
 {
    int wid = 23;
    int ht = 16;
diff --git a/src/NoteTrack.h b/src/NoteTrack.h
index 30a034f22..7ea8a0ccf 100644
--- a/src/NoteTrack.h
+++ b/src/NoteTrack.h
@@ -69,8 +69,8 @@ class AUDACITY_DLL_API NoteTrack final : public Track {
    void WarpAndTransposeNotes(double t0, double t1,
                               const TimeWarper &warper, double semitones);
 
-   int DrawLabelControls(wxDC & dc, wxRect & r);
-   bool LabelClick(wxRect & r, int x, int y, bool right);
+   int DrawLabelControls(wxDC & dc, const wxRect &r);
+   bool LabelClick(const wxRect &rect, int x, int y, bool right);
 
    void SetSequence(std::unique_ptr<Alg_seq> &&seq);
    Alg_seq* GetSequence();