diff --git a/pyproject.toml b/pyproject.toml
index 41c0bcf..ed8f7b6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [build-system]
 requires = [
-    "Cython >= 3.0.3, < 4.0.0",
+    "Cython >= 3.0.3, < 3.1.0",
     "setuptools >= 40.6.0",  # Start of PEP 517 support for setuptools
 ]
 build-backend = "setuptools.build_meta"