diff --git a/pyproject.toml b/pyproject.toml
index 58caf5b..0bbb379 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,6 +32,10 @@ classifiers = [
     "Programming Language :: Python :: Implementation :: PyPy",
     "Typing :: Typed",
     "Operating System :: OS Independent",
+    "Operating System :: MacOS",
+    "Operating System :: Microsoft :: Windows",
+    "Operating System :: POSIX",
+    "Operating System :: Unix",
     "License :: OSI Approved :: GNU Lesser General Public License v3 (LGPLv3)",
     "Intended Audience :: Developers",
     "Intended Audience :: Science/Research",