diff --git a/README.md b/README.md
index 99da456..ce6d7d9 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ See the [NEWS.md](https://github.com/jpmml/sklearn2pmml/blob/master/NEWS.md#0111
 # Prerequisites #
 
 * Java 1.8 or newer. The Java executable must be available on system path.
-* Python 2.7, 3.4 or newer.
+* Python 3.9 or newer.
 
 # Installation #
 
diff --git a/setup.py b/setup.py
index 23a1756..da36a13 100644
--- a/setup.py
+++ b/setup.py
@@ -27,6 +27,7 @@
 	exclude_package_data = {
 		"" : ["README.md"],
 	},
+	python_requires = ">=3.9",
 	install_requires = [
 		"dill>=0.3.4",
 		"joblib>=0.13.0",