diff --git a/src/common/tarstrm.cpp b/src/common/tarstrm.cpp
index ea0c0d14a8..400a4e3989 100644
--- a/src/common/tarstrm.cpp
+++ b/src/common/tarstrm.cpp
@@ -1362,11 +1362,16 @@ void wxTarOutputStream::SetExtendedHeader(const wxString& key,
                                           const wxString& value)
 {
     if (m_pax) {
+#if wxUSE_UNICODE
+        const wxCharBuffer utf_key = key.utf8_str();
+        const wxCharBuffer utf_value = value.utf8_str();
+#else
         const wxWX2WCbuf wide_key = key.wc_str(GetConv());
         const wxCharBuffer utf_key = wxConvUTF8.cWC2MB(wide_key);
 
         const wxWX2WCbuf wide_value = value.wc_str(GetConv());
         const wxCharBuffer utf_value = wxConvUTF8.cWC2MB(wide_value);
+#endif // wxUSE_UNICODE/!wxUSE_UNICODE
 
         // a small buffer to format the length field in
         char buf[32];