diff --git a/setup.py b/setup.py
index 412d4764835d8f5da86c7873280b87bea30f4e71..6cf2f8d7fa6866db420064539806d6812a459590 100644
--- a/setup.py
+++ b/setup.py
@@ -35,6 +35,8 @@ setup(name="pytools",
           'Topic :: Utilities',
           ],
 
+      python_requires='~=3.6',
+
       install_requires=[
           "decorator>=3.2.0",
           "appdirs>=1.4.0",