diff --git a/pyproject.toml b/pyproject.toml
index e738856..6895d77 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ name = "tryton_mcp"
 version = "0.1.0"
 description = "Add your description here"
 readme = "README.md"
-requires-python = ">=3.14"
+requires-python = ">=3.14, <4.0"
 dependencies = [
     "fastmcp[tasks]>=3.1.0",
     "sabatron-tryton-rpc-client>=7.4.0",