diff --git a/build/docker/ubuntu-xenial/Dockerfile b/build/docker/ubuntu-xenial/Dockerfile
index 02b5ac2..e06a0c0 100644
--- a/build/docker/ubuntu-xenial/Dockerfile
+++ b/build/docker/ubuntu-xenial/Dockerfile
@@ -27,7 +27,14 @@
 
 ### Add apt repos
 
-RUN apt-get update && apt-get dist-upgrade -y && apt-get install -y --no-install-recommends apt apt-transport-https curl wget apt-utils
+RUN apt-get update && \
+    apt-get dist-upgrade -y && \
+    apt-get install -y --no-install-recommends \
+      apt \
+      apt-transport-https \
+      apt-utils \
+      curl \
+      wget
 
 # csharp (mono)
 # RUN echo "deb http://download.mono-project.com/repo/debian xenial main" | tee /etc/apt/sources.list.d/mono.list && \
@@ -40,19 +47,14 @@
 
 # Dart
 RUN curl https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - && \
-    curl https://storage.googleapis.com/download.dartlang.org/linux/debian/dart_stable.list > /etc/apt/sources.list.d/dart_stable.list && \
-    sed -i /etc/apt/sources.list.d/dart_stable.list -e 's/https:/http:/g'
-# since ubuntu-artful can't run dart, we'll run 1.240 on xenial for now
+    curl https://storage.googleapis.com/download.dartlang.org/linux/debian/dart_stable.list > \
+      /etc/apt/sources.list.d/dart_stable.list
 ENV DART_VERSION 1.24.2-1
 
 # dotnet (core)
 RUN curl https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > /etc/apt/trusted.gpg.d/microsoft.gpg && \
-    echo "deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-ubuntu-xenial-prod xenial main" > /etc/apt/sources.list.d/dotnetdev.list
-
-# node.js (this step runs apt-get update internally)
-# note: node 8.5 introduced some issues with directory handling / jsdoc / something... using 7.x for now
-# RUN curl -sL https://deb.nodesource.com/setup_7.x | bash
-
+    echo "deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-ubuntu-xenial-prod xenial main" > \
+      /etc/apt/sources.list.d/dotnetdev.list
 
 ### install general dependencies
 RUN apt-get update && apt-get install -y --no-install-recommends \