diff --git a/setup.cfg b/setup.cfg
--- a/setup.cfg
+++ b/setup.cfg
@@ -4,3 +4,6 @@
 # W503: line break before binary operator <https://github.com/psf/black/issues/52>
 ignore = E203,E231,W503
 max-line-length = 88
+
+[options]
+python_requires = >= 3.6