diff --git a/include/wx/mac/pnghand.h b/include/wx/mac/pnghand.h
index 5b43b70d5d..6d4fbfe41e 100644
--- a/include/wx/mac/pnghand.h
+++ b/include/wx/mac/pnghand.h
@@ -29,7 +29,7 @@ public:
 
   virtual bool LoadFile(wxBitmap *bitmap, const wxString& name, long flags,
       int desiredWidth, int desiredHeight);
-  virtual bool SaveFile(wxBitmap *bitmap, const wxString& name, int type, const wxPalette *palette = NULL);
+  virtual bool SaveFile(const wxBitmap *bitmap, const wxString& name, int type, const wxPalette *palette = NULL);
 };
 
 #endif
diff --git a/src/mac/carbon/pnghand.cpp b/src/mac/carbon/pnghand.cpp
index 113365c878..90b59669f0 100644
--- a/src/mac/carbon/pnghand.cpp
+++ b/src/mac/carbon/pnghand.cpp
@@ -887,7 +887,7 @@ bool wxPNGFileHandler::LoadFile(wxBitmap *bitmap, const wxString& name, long fla
         return FALSE;
 }
 
-bool wxPNGFileHandler::SaveFile(wxBitmap *bitmap, const wxString& name, int type, const wxPalette *pal)
+bool wxPNGFileHandler::SaveFile(const wxBitmap *bitmap, const wxString& name, int type, const wxPalette *pal)
 {
     return FALSE;
 }
diff --git a/src/mac/pnghand.cpp b/src/mac/pnghand.cpp
index 113365c878..90b59669f0 100644
--- a/src/mac/pnghand.cpp
+++ b/src/mac/pnghand.cpp
@@ -887,7 +887,7 @@ bool wxPNGFileHandler::LoadFile(wxBitmap *bitmap, const wxString& name, long fla
         return FALSE;
 }
 
-bool wxPNGFileHandler::SaveFile(wxBitmap *bitmap, const wxString& name, int type, const wxPalette *pal)
+bool wxPNGFileHandler::SaveFile(const wxBitmap *bitmap, const wxString& name, int type, const wxPalette *pal)
 {
     return FALSE;
 }