diff --git a/t/Dockerfile b/t/Dockerfile
index 16b427a8..5b0ecb76 100644
--- a/t/Dockerfile
+++ b/t/Dockerfile
@@ -1,11 +1,11 @@
-# DOCKER_NAME=ngcpcfg-bullseye
-FROM docker.mgm.sipwise.com/sipwise-bullseye:latest
+# DOCKER_NAME=ngcpcfg-bookworm
+FROM docker.mgm.sipwise.com/sipwise-bookworm:latest
 
 # Important! Update this no-op ENV variable when this Dockerfile
 # is updated with the current date. It will force refresh of all
 # of the base images and things like `apt-get update` won't be using
 # old cached versions when the Dockerfile is built.
-ENV REFRESHED_AT 2022-08-08
+ENV REFRESHED_AT 2023-06-26
 
 RUN apt-get update && apt-get install --assume-yes libhash-merge-perl libtemplate-perl \
   libyaml-libyaml-perl libyaml-tiny-perl libyaml-perl \
@@ -23,12 +23,12 @@ WORKDIR /code/
 # When you want to build the base image from scratch
 # (jump to the next section if you don't want to build yourself!):
 #
-# % docker build --tag="ngcpcfg-bullseye" -f ./t/Dockerfile .
-# % docker run --rm -i -t -v /tmp/results:/results:rw -v $(pwd):/code:rw ngcpcfg-bullseye:latest bash
+# % docker build --tag="ngcpcfg-bookworm" -f ./t/Dockerfile .
+# % docker run --rm -i -t -v /tmp/results:/results:rw -v $(pwd):/code:rw ngcpcfg-bookworm:latest bash
 #
 # Use the existing docker image:
-# % docker pull docker.mgm.sipwise.com/ngcpcfg-bullseye
-# % docker run --rm -i -t -v /tmp/results:/results:rw -v $(pwd):/code:ro docker.mgm.sipwise.com/ngcpcfg-bullseye:latest bash
+# % docker pull docker.mgm.sipwise.com/ngcpcfg-bookworm
+# % docker run --rm -i -t -v /tmp/results:/results:rw -v $(pwd):/code:ro docker.mgm.sipwise.com/ngcpcfg-bookworm:latest bash
 #
 # Inside docker (the command is in history, just press UP button):
 #   cd /code && ./t/testrunner