diff --git a/README.md b/README.md
index 74df0c9..1f61a29 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,10 @@
 This utility determines if a host appears susceptible to
 [CVE-2019-19781](https://nvd.nist.gov/vuln/detail/CVE-2019-19781).
 
+## Requirements ##
+
+Python versions 3.6 and above.  Note that Python 2 *is not* supported.
+
 ## Installation ##
 
 From a release:
diff --git a/setup.py b/setup.py
index 6598eb1..39ea5be 100644
--- a/setup.py
+++ b/setup.py
@@ -82,6 +82,7 @@ def package_vars(version_file):
             "pytest",
         ]
     },
+    python_requires=">=3.6",
     # Conveniently allows one to run the CLI tool as `cve-2019-19781`
     entry_points={"console_scripts": ["cve-2019-19781=check_cve.check:main"]},
 )