diff --git a/include/wx/string.h b/include/wx/string.h
index 46e95d7351..45c23f3bd0 100644
--- a/include/wx/string.h
+++ b/include/wx/string.h
@@ -3645,7 +3645,7 @@ struct wxStringAsBufHelper<wchar_t>
     {
         wxScopedWCharBuffer wbuf(s.wc_str());
         if ( len )
-            *len = wxWcslen(wbuf);
+            *len = wbuf.length();
         return wbuf;
     }
 };