}
        }
       if (reg == -1)
-       BREAKUP_CHAR (ch, charset, byte1, byte2);
+       {
+         Lisp_Object original_default_coded_charset_priority_list
+           = Vdefault_coded_charset_priority_list;
+
+         while (!EQ (Vdefault_coded_charset_priority_list, Qnil))
+           {
+             BREAKUP_CHAR (ch, charset, byte1, byte2);
+             if (XCHARSET_FINAL (charset))
+               goto found;
+             Vdefault_coded_charset_priority_list
+               = Fcdr (Fmemq (XCHARSET_NAME (charset),
+                              Vdefault_coded_charset_priority_list));
+           }
+         BREAKUP_CHAR (ch, charset, byte1, byte2);
+       found:
+         Vdefault_coded_charset_priority_list
+           = original_default_coded_charset_priority_list;
+       }
       ensure_correct_direction (XCHARSET_DIRECTION (charset),
                                codesys, dst, flags, 0);