diff --git a/pyproject.toml b/pyproject.toml
index 922dd31..4fc151d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ authors = [
     {name = "Chris Proctor",email = "chris@chrisproctor.net"}
 ]
 readme = "README.md"
-requires-python = ">=3.10"
+requires-python = ">=3.10,<4.0"
 dependencies = [
 ]