diff --git a/requirements.txt b/requirements.txt
index 0e62ea872..1f3f27179 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,7 @@
 setuptools>=18.8.1
+# pycparser is a transitive dependency of cryptography. 2.18 is the last
+# release with Python 2.6 support
+pycparser==2.18 ; python_version=="2.6"
 cryptography>=1.4
 boto3>=1.1.3
 ruamel.yaml>=0.11.7,<0.12.0 ; python_version=="2.6"
diff --git a/setup.py b/setup.py
index 2b1a919aa..374f6b5d6 100755
--- a/setup.py
+++ b/setup.py
@@ -23,6 +23,9 @@ setup(
         'ruamel.yaml>=0.11.7,<0.12.0 ; python_version=="2.6"',
         'ruamel.yaml>=0.11.7 ; python_version>"2.6"',
         'boto3>=1.1.3',
+        # pycparser is a transitive dependency of cryptography. 2.18 is the
+        # last release with Python 2.6 support
+        'pycparser==2.18 ; python_version=="2.6"',
         'cryptography>=1.4',
         'setuptools>=18.8.1',
         'ordereddict>=1.1',