diff --git a/clamd/Dockerfile b/clamd/Dockerfile
index 5e0e9bc04b1e45acc842c26a32689c5fa89bceaf..8d28a19291e4136495eedfe397838223c57aca56 100644
--- a/clamd/Dockerfile
+++ b/clamd/Dockerfile
@@ -1,4 +1,4 @@
-FROM docker.io/debian:bullseye-slim
+FROM docker.io/debian:bookworm-slim
 # hadolint ignore=DL3008
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
diff --git a/dovecot/Dockerfile b/dovecot/Dockerfile
index 550793b67d81eb992d310419399dbfa548f57f9a..6c8325841f51f33f8382a444ca8b14ab56266a0c 100644
--- a/dovecot/Dockerfile
+++ b/dovecot/Dockerfile
@@ -1,11 +1,11 @@
-FROM docker.io/buildpack-deps:bullseye as delete_to_trash
+FROM docker.io/buildpack-deps:bookworm as delete_to_trash
 # hadolint ignore=DL3008,DL3015
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive  apt-get install -y dovecot-dev && \
     git clone https://github.com/pali/dovecot_deleted_to_trash && \
     make -C dovecot_deleted_to_trash
 
-FROM docker.io/debian:bullseye-slim
+FROM docker.io/debian:bookworm-slim
 # hadolint ignore=DL3008
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
diff --git a/exim4/Dockerfile b/exim4/Dockerfile
index 9c2babc9e4bc9b9e203982f7d953898181228aa4..a378ac81c2070379bf3142cc658ecf620ffc3749 100644
--- a/exim4/Dockerfile
+++ b/exim4/Dockerfile
@@ -1,4 +1,4 @@
-FROM docker.io/debian:bullseye-slim
+FROM docker.io/debian:bookworm-slim
 # hadolint ignore=DL3008,DL4006
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
diff --git a/spamd/Dockerfile b/spamd/Dockerfile
index 3acaaf24b4729bd60e8f595ee1a13ee395a8cea7..60affd6b61e1af5cfe1dc6c1acc133254f6cc230 100644
--- a/spamd/Dockerfile
+++ b/spamd/Dockerfile
@@ -1,4 +1,4 @@
-FROM docker.io/debian:bullseye-slim
+FROM docker.io/debian:bookworm-slim
 # hadolint ignore=DL3008
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \