diff --git a/setup.py b/setup.py
index 2e2478d91c402780b0b692c2de436315bfe7742f..ec096cbcc583df439cc99bbdeccddca16a5ba824 100644
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,7 @@ setup(name="pytools",
           'Topic :: Utilities',
           ],
 
+      python_requires="~=3.6",
       install_requires=[
           "decorator>=3.2.0",
           "appdirs>=1.4.0",