diff --git a/acme/setup.py b/acme/setup.py
index 3b1a42327..4993d7584 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -6,6 +6,7 @@ from setuptools import find_packages
 
 version = '0.2.0.dev0'
 
+# Please update tox.ini when modifying dependency version requirements
 install_requires = [
     # load_pem_private/public_key (>=0.6)
     # rsa_recover_prime_factors (>=0.8)
diff --git a/letsencrypt-apache/setup.py b/letsencrypt-apache/setup.py
index 58008e1e4..a5c5e8a7a 100644
--- a/letsencrypt-apache/setup.py
+++ b/letsencrypt-apache/setup.py
@@ -6,6 +6,7 @@ from setuptools import find_packages
 
 version = '0.2.0.dev0'
 
+# Please update tox.ini when modifying dependency version requirements
 install_requires = [
     'acme=={0}'.format(version),
     'letsencrypt=={0}'.format(version),
diff --git a/letsencrypt-nginx/setup.py b/letsencrypt-nginx/setup.py
index 1d42fe488..bfb3c3758 100644
--- a/letsencrypt-nginx/setup.py
+++ b/letsencrypt-nginx/setup.py
@@ -6,6 +6,7 @@ from setuptools import find_packages
 
 version = '0.2.0.dev0'
 
+# Please update tox.ini when modifying dependency version requirements
 install_requires = [
     'acme=={0}'.format(version),
     'letsencrypt=={0}'.format(version),
diff --git a/setup.py b/setup.py
index f95f672ff..ad7fb6909 100644
--- a/setup.py
+++ b/setup.py
@@ -30,6 +30,7 @@ readme = read_file(os.path.join(here, 'README.rst'))
 changes = read_file(os.path.join(here, 'CHANGES.rst'))
 version = meta['version']
 
+# Please update tox.ini when modifying dependency version requirements
 install_requires = [
     'acme=={0}'.format(version),
     'configobj',