diff --git a/include/wx/textbuf.h b/include/wx/textbuf.h
index c7087c669a..32d8379a0d 100644
--- a/include/wx/textbuf.h
+++ b/include/wx/textbuf.h
@@ -81,10 +81,10 @@ public:
     bool Create(const wxString& strBufferName);
 
     // Open() also loads buffer in memory on success
-    bool Open(wxMBConv& conv = wxConvLibc);
+    bool Open(wxMBConv& conv = wxConvISO8859_1);
 
     // same as Open() but with (another) buffer name
-    bool Open(const wxString& strBufferName, wxMBConv& conv = wxConvLibc);
+    bool Open(const wxString& strBufferName, wxMBConv& conv = wxConvISO8859_1);
 
     // closes the buffer and frees memory, losing all changes
     bool Close();
@@ -148,7 +148,7 @@ public:
     // change the buffer (default argument means "don't change type")
     // possibly in another format
     bool Write(wxTextFileType typeNew = wxTextFileType_None,
-               wxMBConv& conv = wxConvLibc);
+               wxMBConv& conv = wxConvISO8859_1);
 
     // dtor
     virtual ~wxTextBuffer();
@@ -171,8 +171,7 @@ protected:
                         wxTextBufferOpenMode openmode) = 0;
     virtual bool OnClose() = 0;
     virtual bool OnRead(wxMBConv& conv) = 0;
-    virtual bool OnWrite(wxTextFileType typeNew,
-                        wxMBConv& conv = wxConvLibc) = 0;
+    virtual bool OnWrite(wxTextFileType typeNew, wxMBConv& conv) = 0;
 
     wxString m_strBufferName;  // name of the buffer
 
diff --git a/include/wx/textfile.h b/include/wx/textfile.h
index b66afc76c4..43024f64db 100644
--- a/include/wx/textfile.h
+++ b/include/wx/textfile.h
@@ -44,7 +44,7 @@ protected:
                         wxTextBufferOpenMode OpenMode);
     virtual bool OnClose();
     virtual bool OnRead(wxMBConv& conv);
-    virtual bool OnWrite(wxTextFileType typeNew, wxMBConv& conv = wxConvLibc);
+    virtual bool OnWrite(wxTextFileType typeNew, wxMBConv& conv);
 
 private:
     wxFile m_file;