diff --git a/Dockerfile b/Dockerfile
index b054fb1..fedb3de 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,17 +1,25 @@
 FROM ubuntu:14.04.4
 
-RUN apt-get update -y
-RUN apt-get install -y python-setuptools python-dev build-essential libffi-dev libssl-dev
+RUN apt-get update \
+ && apt-get install -y -q --no-install-recommends \
+    build-essential \
+    libffi-dev \
+    libssl-dev \
+    python-dev \
+    python-setuptools \
+ && apt-get clean \
+ && rm -r /var/lib/apt/lists/*
 
 WORKDIR /opt
 ADD . /opt/app
 WORKDIR /opt/app
 
-RUN python setup.py build
-RUN python setup.py install
+RUN python setup.py build \
+ && python setup.py install
 
 ADD docker/run.sh /opt/run.sh
 
 EXPOSE 57575
 
-ENTRYPOINT ["/opt/run.sh"]
+CMD ["butterfly.server.py", "--unsecure", "--host=0.0.0.0"]
+ENTRYPOINT ["docker/run.sh"]
diff --git a/README.md b/README.md
index 20ad40e..00f159f 100644
--- a/README.md
+++ b/README.md
@@ -114,7 +114,7 @@ Starting with login and password
 docker run \
 --env PASSWORD=password \
 -p 57575:57575 \
--d garland/butterfly --unsecure --host=0.0.0.0 --port=57575 --login
+-d garland/butterfly --port=57575 --login
 ```
 
 Starting with no password
@@ -123,5 +123,5 @@ Starting with no password
 docker run \
 --env PORT=57575 \
 -p 57575:57575 \
--d garland/butterfly --unsecure --host=0.0.0.0 --port=57575
+-d garland/butterfly --port=57575
 ```
diff --git a/docker/run.sh b/docker/run.sh
index b7e11f9..c18acd3 100755
--- a/docker/run.sh
+++ b/docker/run.sh
@@ -1,6 +1,14 @@
-#!/bin/sh -x
+#!/bin/bash -e
+
+# if command starts with an option, prepend the default command and options
+if [ "${1:0:1}" = '-' ]; then
+  set -- butterfly.server.py --unsecure --host=0.0.0.0 --port=${PORT:-57575} "$@"
+elif [ "$1" = 'butterfly.server.py' ]; then
+  shift
+  set -- butterfly.server.py --unsecure --host=0.0.0.0 --port=${PORT:-57575} "$@"
+fi
 
 # Set password
-echo "root:${PASSWORD}" | chpasswd
+echo "root:${PASSWORD:-password}" | chpasswd
 
-/opt/app/butterfly.server.py $@
+exec "$@"