Control: tags -1 +patch The upstream bugs was closed and fixed with this patch: https://gitlab.com/embeddable-common-lisp/ecl/commit/bd48b85970603af16318ec56d6da50a71c9d129e.diff Could you please apply it? We have been using a patched ecl 15.3.7 package for a while and it solves the problem with sagemath. Best, Tobias