diff --git a/src/ifcopenshell-python/pyproject.toml b/src/ifcopenshell-python/pyproject.toml
index cf65b9de30..b80eefb3ac 100644
--- a/src/ifcopenshell-python/pyproject.toml
+++ b/src/ifcopenshell-python/pyproject.toml
@@ -9,6 +9,7 @@ authors = [
 ]
 description = "Python bindings, utility functions, and high-level API for IfcOpenShell"
 readme = "README.md"
+requires-python = ">=3.6,<3.12"
 classifiers = [
     "Programming Language :: Python :: 3",
     "License :: OSI Approved :: GNU Lesser General Public License v3 or later (LGPLv3+)",