diff --git a/t/Dockerfile b/t/Dockerfile
index f453815..915262c 100644
--- a/t/Dockerfile
+++ b/t/Dockerfile
@@ -5,17 +5,17 @@ FROM docker.mgm.sipwise.com/sipwise-stretch:latest
 # 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 2017-09-25
+ENV REFRESHED_AT 2019-07-02
 
-# TODO - the release-trunk-stretch is too dynamic yet, though required build deps
-RUN echo "deb https://deb.sipwise.com/autobuild/ release-trunk-stretch main" >>/etc/apt/sources.list
+COPY t/sources.list.d/builddeps.list /etc/apt/sources.list.d/
+COPY t/sources.list.d/preferences /etc/apt/preferences.d/
 
-RUN apt-get update
-RUN apt-get install --assume-yes \
+RUN apt-get update && \
+  apt-get install --assume-yes \
         curl \
         nodejs \
-        nodejs-legacy \
-        npm
+        && \
+  apt-get clean
 
 ADD package.json /tmp/
 ADD npm-shrinkwrap.json /tmp/
@@ -30,10 +30,13 @@ RUN echo "cd /code && ./t/testrunner" >/root/.bash_history
 WORKDIR /code
 
 ################################################################################
-# Instructions for usage
+# Instructions for usage (from root folder of git repository)
 # ----------------------
-# When you want to build the base image from scratch (jump to the next section if you don't want to build yourself!):
-# NOTE: run the following commands from root folder of git repository:
+# When you want to build the base image from scratch
+# (jump to the next section if you don't want to build yourself!).
+# The first you need to put the proper NGCP sources at t/sources.list.d/builddeps.list
+# for instance, trunk:
+# % echo "deb https://deb.sipwise.com/autobuild/ release-trunk-buster main" > t/sources.list.d/builddeps.list
 # % docker build --tag="janus-admin-stretch" -f ./t/Dockerfile .
 # % docker run --rm -i -t -v $(pwd):/code:ro -v /results janus-admin-stretch:latest bash
 #
diff --git a/t/sources.list.d/builddeps.list b/t/sources.list.d/builddeps.list
new file mode 100644
index 0000000..e69de29
diff --git a/t/sources.list.d/preferences b/t/sources.list.d/preferences
new file mode 100644
index 0000000..e69de29