diff --git a/Dockerfile b/Dockerfile
index 1bf2fc1f..46c5d7b9 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,4 +5,4 @@ WORKDIR /usr/src/app
 # use this to test a SLACK_TOKEN environment variable
 # ENV SLACK_TOKEN ###token###
 
-RUN python run.py
+CMD python run.py
diff --git a/slackbot/settings.py b/slackbot/settings.py
index d692c536..fa8fc2dd 100644
--- a/slackbot/settings.py
+++ b/slackbot/settings.py
@@ -1,4 +1,5 @@
 import os
+import sys
 
 DEBUG = False
 
@@ -14,6 +15,7 @@
     # Alternatively, place slack token in the source code
     # API_TOKEN = '###token###'
     print 'SLACK_TOKEN missing'
+    sys.exit(1)
 
 '''
 If you use Slack Web API to send messages (with send_webapi() or reply_webapi()),