diff --git a/docker/spark-test/base/Dockerfile b/docker/spark-test/base/Dockerfile
index 5956d59130..5dbdb8b22a 100644
--- a/docker/spark-test/base/Dockerfile
+++ b/docker/spark-test/base/Dockerfile
@@ -17,13 +17,13 @@
 
 FROM ubuntu:precise
 
-RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe" > /etc/apt/sources.list
-
 # Upgrade package index
-RUN apt-get update
-
 # install a few other useful packages plus Open Jdk 7
-RUN apt-get install -y less openjdk-7-jre-headless net-tools vim-tiny sudo openssh-server
+# Remove unneeded /var/lib/apt/lists/* after install to reduce the
+# docker image size (by ~30MB)
+RUN apt-get update && \
+    apt-get install -y less openjdk-7-jre-headless net-tools vim-tiny sudo openssh-server && \
+    rm -rf /var/lib/apt/lists/*
 
 ENV SCALA_VERSION 2.10.4
 ENV CDH_VERSION cdh4