diff --git a/pyproject.toml b/pyproject.toml
index 03345f4..3cd2956 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,6 +12,7 @@ description = "Object-orientated Python interface to pyGPlates for plate tectoni
 readme = "README.md"
 authors = [{ name = "Ben Mather", email = "ben.mather@sydney.edu.au" }]
 license = { file = "LICENSE" }
+requires-python = ">= 3.8" # At least Python 3.8
 classifiers = [
     "License :: OSI Approved :: GNU General Public License v2 (GPLv2)",
     "Programming Language :: Python",
diff --git a/setup.py b/setup.py
index a3b67e7..cbf50e7 100644
--- a/setup.py
+++ b/setup.py
@@ -110,6 +110,7 @@ def _minimal_ext_cmd(cmd):
         #    ]
         # },
         include_package_data=True,
+        python_requires=">=3.8",
         classifiers=[
             "Programming Language :: Python :: 3",
             "Programming Language :: Python :: 3.8",