diff --git a/imagebuild/coreos/oem/system/teeth-agent.service b/imagebuild/coreos/oem/system/teeth-agent.service
index 60d853934..a25c2ba7d 100644
--- a/imagebuild/coreos/oem/system/teeth-agent.service
+++ b/imagebuild/coreos/oem/system/teeth-agent.service
@@ -1,5 +1,5 @@
 [Service]
-ExecStart=/usr/bin/docker run -p 9999:9999 -privileged=true -v=/sys:/mnt/sys oemdocker /usr/local/bin/teeth-agent
+ExecStart=/usr/bin/docker run -p 9999:9999 -privileged=true -v=/sys:/mnt/sys oemdocker /usr/local/bin/teeth-agent --ipaddr="`ip a | grep '10\.' | sed -e 's/inet \(10\.[0-9\.]\+\).*/\1/'`"
 Restart=always
 
 [Install]
diff --git a/teeth_agent/agent.py b/teeth_agent/agent.py
index 3632bd0cb..b8efe5f56 100644
--- a/teeth_agent/agent.py
+++ b/teeth_agent/agent.py
@@ -107,9 +107,10 @@ class TeethAgentHeartbeater(threading.Thread):
 
 
 class TeethAgent(object):
-    def __init__(self, api_url, listen_address):
+    def __init__(self, api_url, listen_address, ipaddr):
         self.api_url = api_url
         self.listen_address = listen_address
+        self.ipaddr = ipaddr
         self.mode_implementation = None
         self.version = pkg_resources.get_distribution('teeth-agent').version
         self.api = api.TeethAgentAPIServer(self)
@@ -217,5 +218,5 @@ def _load_mode_implementation(mode_name):
     return mgr.driver
 
 
-def build_agent(api_url, listen_host, listen_port):
-    return TeethAgent(api_url, (listen_host, listen_port))
+def build_agent(api_url, listen_host, listen_port, ipaddr):
+    return TeethAgent(api_url, (listen_host, listen_port), ipaddr)
diff --git a/teeth_agent/cmd/agent.py b/teeth_agent/cmd/agent.py
index bdfa8d41d..92f4ef386 100644
--- a/teeth_agent/cmd/agent.py
+++ b/teeth_agent/cmd/agent.py
@@ -39,8 +39,13 @@ def run():
                         type=int,
                         help='The port to listen on')
 
+    parser.add_argument('--ipaddr',
+                        required=True,
+                        help='The external IP address to advertise to ironic')
+
     args = parser.parse_args()
     logging.configure()
     agent.build_agent(args.api_url,
                       args.listen_host,
-                      args.listen_port).run()
+                      args.listen_port,
+                      args.ipaddr).run()
diff --git a/teeth_agent/tests/agent.py b/teeth_agent/tests/agent.py
index f1d4ed20c..5e46f6bd6 100644
--- a/teeth_agent/tests/agent.py
+++ b/teeth_agent/tests/agent.py
@@ -121,7 +121,8 @@ class TestBaseAgent(unittest.TestCase):
             encoding.SerializationViews.PUBLIC,
             indent=4)
         self.agent = agent.TeethAgent('https://fake_api.example.org:8081/',
-                                      ('localhost', 9999))
+                                      ('localhost', 9999),
+                                      '192.168.1.1')
 
     def assertEqualEncoded(self, a, b):
         # Evidently JSONEncoder.default() can't handle None (??) so we have to