diff --git a/core/base/Dockerfile b/core/base/Dockerfile
index 2f49c5ad..e2a48551 100644
--- a/core/base/Dockerfile
+++ b/core/base/Dockerfile
@@ -3,7 +3,7 @@
 # base system image (intermediate)
 # Note when updating the alpine tag, first manually run the workflow .github/workflows/mirror.yml.
 # Just run the workflow with the tag that must be synchronised.
-ARG DISTRO=ghcr.io/mailu/alpine:3.20.3
+ARG DISTRO=ghcr.io/mailu/alpine:3.21.0
 FROM $DISTRO as system
 
 ENV TZ=Etc/UTC LANG=C.UTF-8
diff --git a/core/nginx/Dockerfile b/core/nginx/Dockerfile
index 41992f30..52afff72 100644
--- a/core/nginx/Dockerfile
+++ b/core/nginx/Dockerfile
@@ -17,8 +17,7 @@ ARG VERSION
 LABEL version=$VERSION
 
 RUN set -euxo pipefail \
-  ; apk add --no-cache certbot nginx nginx-mod-http-brotli nginx-mod-mail openssl \
-  ; apk add --no-cache --repository=http://dl-cdn.alpinelinux.org/alpine/edge/main dovecot-lua dovecot-pigeonhole-plugin 'dovecot-lmtpd<2.4' dovecot-pop3d dovecot-submissiond
+  ; apk add --no-cache certbot nginx nginx-mod-http-brotli nginx-mod-mail openssl dovecot-lua dovecot-pigeonhole-plugin 'dovecot-lmtpd<2.4' dovecot-pop3d dovecot-submissiond
 
 COPY conf/ /conf/
 COPY --from=static /static/ /static/