Hi Efraim and Ludo! This patch could be an starting point to even master, it allows to extend easily glibc-utf8-locales to the desired ones. I've used the following steps to test it[1]: ------------------------------>8---------------------------------- $ echo '(define-module (t) #:use-module (gnu packages base)) (define-public glibc-utf8-test (make-glibc-utf8-locales glibc #:locales (list "es_ES") #:name "glibc-utf8-test")) glibc-utf8-test' > tmp/t.scm $ ./pre-inst-env guix build -f tmp/t.scm $ ./pre-inst-env guix package -L tmp --show=glibc-utf8-test ------------------------------8<---------------------------------- Something like glibc-utf8--locales could be easily implemented on top of this, and I think it could be helpful for the end user too. WDYT? Happy hacking! Miguel [1] After checking that ./pre-inst-env guix build glibc-utf8-locales didn't rebuild anything at all, of course.