diff --git a/pyproject.toml b/pyproject.toml
index 0ba039a129be..9a3d25dbee38 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,7 +46,7 @@ classifiers = [
     "Programming Language :: Python :: Implementation :: PyPy",
     "Topic :: Security :: Cryptography",
 ]
-requires-python = ">=3.7"
+requires-python = ">=3.7,!=3.9.0,!=3.9.1"
 dependencies = [
     # Must be kept in sync with `build-system.requires`
     "cffi>=1.12; platform_python_implementation != 'PyPy'",