diff --git a/acme/setup.py b/acme/setup.py
index 8ce3399cc..17bc494c8 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -1,3 +1,5 @@
+import sys
+
 from setuptools import setup
 from setuptools import find_packages
 
@@ -18,6 +20,11 @@ install_requires = [
     'werkzeug',
 ]
 
+# env markers in extras_require cause problems with older pip: #517
+if sys.version_info < (2, 7):
+    # only some distros recognize stdlib argparse as already satisfying
+    install_requires.append('argparse')
+
 testing_extras = [
     'nose',
     'tox',
diff --git a/setup.py b/setup.py
index 1e0d58a70..8d1e264fc 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,7 @@
 import codecs
 import os
 import re
+import sys
 
 from setuptools import setup
 from setuptools import find_packages
@@ -30,7 +31,6 @@ changes = read_file(os.path.join(here, 'CHANGES.rst'))
 
 install_requires = [
     'acme',
-    'argparse',
     'ConfigArgParse',
     'configobj',
     'cryptography>=0.7',  # load_pem_x509_certificate
@@ -46,6 +46,11 @@ install_requires = [
     'zope.interface',
 ]
 
+# env markers in extras_require cause problems with older pip: #517
+if sys.version_info < (2, 7):
+    # only some distros recognize stdlib argparse as already satisfying
+    install_requires.append('argparse')
+
 dev_extras = [
     # Pin astroid==1.3.5, pylint==1.4.2 as a workaround for #289
     'astroid==1.3.5',