Hello For some reason, errors in macro expansion don't trigger the debugger. This may be on purpose, but it makes macro debugging difficult. Gladly, I've found a workaround: run (current-exception-handler primordial-exception-handler) before expansion of the faulty macro, or (with-exception-handler primordial-exception-handler (eval '(code-containing-calls-to-faulty-macro))) but using eval disconnects the code from the lexical environment. Now I'm looking for a simpler way to turn macro debugging on. I've thought about a macro; since using eval is out of question (because of breaking lexical env), I wanted to work around this by saving and restoring the current handler manually: (define-macro (cj-env#insert-result-of expr) (eval expr)) (define-macro (with-macro-debugging body) `(begin (cj-env#insert-result-of (begin (define | saved-exception-handler| (current-exception-handler)) (warn "saved:" | saved-exception-handler|) (current-exception-handler primordial-exception-handler) (warn "now is:" (current-exception-handler)) '(begin))) ,body (cj-env#insert-result-of (begin (warn "put back:" | saved-exception-handler|) (current-exception-handler | saved-exception-handler|) (warn "now is:" (current-exception-handler)) '(begin)))))) But this won't work because the macro call after ,body isn't allowed, see my former mail about (begin). What are your suggestions? Cheers Christian.