diff --git a/src/TrackArtist.cpp b/src/TrackArtist.cpp
index ab287995f..15d856a5d 100644
--- a/src/TrackArtist.cpp
+++ b/src/TrackArtist.cpp
@@ -321,9 +321,9 @@ void TrackArtist::SetInset(int left, int top, int right, int bottom)
 void TrackArtist::DrawTracks(TrackList * tracks,
                              Track * start,
                              wxDC & dc,
-                             wxRegion & reg,
-                             wxRect & rect,
-                             wxRect & clip,
+                             const wxRegion & reg,
+                             const wxRect & rect,
+                             const wxRect & clip,
                              const SelectedRegion &selectedRegion,
                              const ZoomInfo &zoomInfo,
                              bool drawEnvelope,
diff --git a/src/TrackArtist.h b/src/TrackArtist.h
index 4351ec1db..5ca3a190c 100644
--- a/src/TrackArtist.h
+++ b/src/TrackArtist.h
@@ -53,8 +53,8 @@ class AUDACITY_DLL_API TrackArtist {
 
    void SetColours();
    void DrawTracks(TrackList *tracks, Track *start,
-                   wxDC & dc, wxRegion & reg,
-                   wxRect & rect, wxRect & clip,
+                   wxDC & dc, const wxRegion & reg,
+                   const wxRect & rect, const wxRect & clip,
                    const SelectedRegion &selectedRegion, const ZoomInfo &zoomInfo,
                    bool drawEnvelope, bool bigPoints, bool drawSliders);
 
diff --git a/src/TrackPanel.cpp b/src/TrackPanel.cpp
index edbde6b45..fc7fb58dc 100644
--- a/src/TrackPanel.cpp
+++ b/src/TrackPanel.cpp
@@ -7091,7 +7091,7 @@ void TrackPanel::DrawTracks(wxDC * dc)
 {
    wxRegion region = GetUpdateRegion();
 
-   wxRect clip = GetRect();
+   const wxRect clip = GetRect();
 
    wxRect panelRect = clip;
    panelRect.y = -mViewInfo->vpos;