diff --git a/pyproject.toml b/pyproject.toml
index 6f12720..90a526b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,6 +12,7 @@ authors = [
     { name = "Xianpeng Shen", email = "xianpeng.shen@gmail.com" },
     { name = "Brendan Doherty", email = "2bndy5@gmail.com" },
 ]
+requires-python = ">=3.9"
 classifiers = [
     # https://pypi.org/pypi?%3Aaction=list_classifiers
     "Development Status :: 5 - Production/Stable",
@@ -22,7 +23,11 @@ classifiers = [
     "Operating System :: Microsoft :: Windows",
     "Operating System :: POSIX :: Linux",
     "Operating System :: MacOS",
-    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "Topic :: Software Development :: Build Tools",
 ]
 dynamic = ["version"]