diff --git a/.circleci/config.yml b/.circleci/config.yml
index c8de0688..a745c37c 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -124,7 +124,7 @@ jobs:
           command: |
             if [ "${DOCKER_EMAIL}" == 'googleapis-publisher@google.com' ]; then
               # extract version number from setup.py
-              ARTMAN_VERSION=`awk -F"'" '/current_version =/ { print $2; }' setup.py`
+              ARTMAN_VERSION=`awk '/ENV ARTMAN_VERSION/ { print $3; }' Dockerfile`
               # push to docker
               docker login -e "${DOCKER_EMAIL}" -u "${DOCKER_USER}" -p "${DOCKER_PASS}"
               docker tag artman "googleapis/artman:AUTO_BUILD_$CIRCLE_BUILD_NUM"
diff --git a/Dockerfile b/Dockerfile
index 034c4a34..8ea5834b 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,6 +3,8 @@ FROM ubuntu:16.04
 # Release parameters
 ENV GOOGLEAPIS_HASH 837973f525ecf5f0cb1cfa2bd8fc85e936d4c6c9
 ENV GAPIC_GENERATOR_HASH 48441a7c3382583d5887a9db7286fb0fb93223e7
+# Define version number below. The ARTMAN_VERSION line is parsed by
+# .circleci/config.yml and setup.py, please keep the format.
 ENV ARTMAN_VERSION 0.15.5
 
 ENV DEBIAN_FRONTEND noninteractive
diff --git a/setup.py b/setup.py
index 3d31766b..4c0b34ba 100644
--- a/setup.py
+++ b/setup.py
@@ -19,14 +19,25 @@
 
 import io
 import os
+import re
 import setuptools
 
-# The following line is parsed by CI scripts (see .circleci/config.yml)
-# and by release.py. Please keep the format.
-current_version = '0.15.5'
-
 cur_dir = os.path.realpath(os.path.dirname(__file__))
-with io.open('%s/requirements.txt' % cur_dir) as requirements_file:
+
+# version is defined in Dockerfile: ENV ARTMAN_VERSION version
+current_version = None
+with io.open(os.path.join(cur_dir, 'Dockerfile')) as dockerfile:
+    for line in dockerfile:
+        match = re.match('^ENV ARTMAN_VERSION (\S+)$', line)
+        if match:
+            current_version = match.group(1)
+            break
+if not current_version:
+    print('Cannot determine version from Dockerfile. Exiting.')
+    exit(1)
+print('Version: %s' % current_version)
+
+with io.open(os.path.join(cur_dir, 'requirements.txt')) as requirements_file:
     requirements = requirements_file.read().strip().split('\n')
 
 setuptools.setup(
diff --git a/update-versions.py b/update-versions.py
index fb521aee..00e0358e 100644
--- a/update-versions.py
+++ b/update-versions.py
@@ -30,7 +30,6 @@
 dockerfile_googleapis_regex = r'^(ENV GOOGLEAPIS_HASH )\S+()'
 dockerfile_gapic_generator_regex = r'^(ENV GAPIC_GENERATOR_HASH )\S+()'
 dockerfile_version_regex = r'^(ENV ARTMAN_VERSION )\S+()'
-setup_py_version_regex = r"^(current_version = ')\S+(')"
 
 github_gapic_generator_project = 'googleapis/gapic-generator'
 github_googleapis_project = 'googleapis/googleapis'
@@ -139,7 +138,6 @@ def main():
     abspath = os.path.abspath(parser.prog)
     root_dir = os.path.dirname(abspath)
     dockerfile = os.path.join(root_dir, 'Dockerfile')
-    setup_py = os.path.join(root_dir, 'setup.py')
 
     # Do what they asked
     if googleapis_sha:
@@ -153,7 +151,6 @@ def main():
 
     if args.version:
         update_file(dockerfile, dockerfile_version_regex, args.version)
-        update_file(setup_py, setup_py_version_regex, args.version)
         print('Version is now ' + args.version + '.')