diff --git a/pyproject.toml b/pyproject.toml
index eafccb77f..a436bf5c6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,7 @@
+[build-system]
+requires = ["setuptools >= 77.0.3"]
+build-backend = "setuptools.build_meta"
+
 [tool.cibuildwheel]
 build-verbosity = "3"
 test-command = [
diff --git a/setup.py b/setup.py
index c816a0c5e..04fb5c4f9 100644
--- a/setup.py
+++ b/setup.py
@@ -987,7 +987,7 @@ if __name__ == "__main__":
     setup(
         name=config.root,
         version=config.version(),
-        license="GNU GPLv3",
+        license="GPL-3.0-or-later",
         description="KLayout standalone Python package",
         long_description="This package is a standalone distribution of KLayout's Python API.\n\nFor more details see here: https://www.klayout.org/klayout-pypi",
         author="Matthias Koefferlein",
@@ -996,7 +996,6 @@ if __name__ == "__main__":
             # Recommended classifiers
             "Programming Language :: Python :: 2",
             "Programming Language :: Python :: 3",
-            "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
             "Operating System :: MacOS :: MacOS X",
             "Operating System :: Microsoft :: Windows",
             "Operating System :: POSIX :: Linux",