diff --git a/pyproject.toml b/pyproject.toml
index 384f0e5d..c9ab0c9f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,6 +5,6 @@ requires = ["setuptools",
             "wheel",
             "extension-helpers",
             "oldest-supported-numpy",
-            "cython>=0.29.23,<3.0.0"]
+            "cython>=0.29.23,<4.0.0"]
 
 build-backend = 'setuptools.build_meta'